FDN Facts II Flashcards
(140 cards)
1
Q
Importance of Glycosis is… (2)
A
- release of free energy for growth…. etc
- formation of intermediate compounds
etc… growth, replication, for the generation of electrical impulses or heat, and for the performance of such metabolic work as muscle contraction, absorption against concentration gradients, synthesis of proteins
2
Q
Glycolysis makes up __ % of body’s total ATP
A
60%
3
Q
Intermediate glycolytic compounds contribute to other pathways (2)
A
- DHAP –> Triglycerides
2. Pyruvate –> Alanine Synthesis
4
Q
What can inhibit hexokinase and only in what tissue types can it be done?
A
G6Phosphatase can reverse the reaction to convert G6P into glucose when G6P levels are too high! G6Phosphatase is found only in the liver and kidney to release trapped glucose into the blood.
5
Q
Anabolic and Catabolic. Which requires energy, which is ox/red?
A
Anabolic requires energy and is reductive. Catabolic releases energy and is oxidative.
6
Q
Three irreversible reactions
A
- Hexokinase
- Phosphofructokinase (rate limiting step)
- Pyruvate Kinase
7
Q
Phosphofructokinase is allosterically regulated by?
A
+ Fructose 2,6-Biphosphate, AMP
- ATP, citrate
8
Q
Aldolase is the reverse of ?
A
Aldo condensation
9
Q
Triose phosphate DH (GAL 3P DH) is important because?
A
Sulfhydryl groups are involved in the enzymatic reaction and may be inactivated by SH poison iodoacetate.
10
Q
What stages are 2 molecules of ATP formed?
A
Phosphoglycerate kinase and pyruvate kinase
11
Q
Moles of ATP per NADH and FADH2
A
2.5-3 & 1.5-2 moles of ATP
12
Q
Name all the types of enzymes used in Glycolysis (6)
A
- Phosphoryl transfer (Hexokinase, Phosphofructokinase, phosphoglycerate kinase, pyruvate kinase)
- Phosphoryl Shift (Phosphoglyercerate mutase)
- Isomerization (Phosphoglucose isomerase, Triose Phosphate Isomerase)
- Dehydration (Enolase)
- Aldol Cleavage (Aldolase)
- Phosphorylation coupled to oxidation (GAL 3P DH)
13
Q
Gluconeogenesis occurs in what tissues?
A
Liver and Kidney and is much needed esp. for tissues of high glucose demand like brain and exercising muscle.
14
Q
Which steps in glycolysis produces a high energy P-bond?
A
3PGAL –GAL 3P DH–> 1,3 BPGA
2PGA –Enolase –> PEP
15
Q
Premature and smaller than normal infants are different to normal sized infants in terms of becoming hypoglycemic. Why?
A
They have smaller liver glycogen stores and fasting depletes their stores and have then rely on gluconeogenesis.
16
Q
What are the distinctive reactions of gluconeogenesis?
A
- Carboxylation of Pyruvate to oxaloacetate
- Decarboxylation and phosphorylation of oxaloacetate to PEP
- Reversal of the rxns catalyzed by phosphofructokinase and hexokinase.
17
Q
List the enzymes of gluconeogenesis that reverse rxns of glycolysis
A
- [ pyruvate carboxylase (only in mt. matrix) & PEP carboxylase ] reverse pyruvate kinase
- Fructose 1,6 Bisphophatase reverse phosphofructokinase
- Glucose 6 phosphatase reverse hexokinase
18
Q
Insulin inhibits?
cortisol stimulates?
A
PEP carboxykinase & Glucose 6 Phosphatase
19
Q
Glucagon inhibits the?
A
Inhibitor (Fructose 2,6 BiPhosphate) which inhibits F 1,6 Bisphosphates.
Glucagon phosphorylates Phosphofructokinase which becomes F 2,6 Bisphosphatase to degrade F 2,6 Bisphosphate
20
Q
Substrates for Gluconeogenesis
A
lactate, amino acids, glycerol
21
Q
To improve treating diabetic, burn victim, or post operative pt we hyperaliment which is what?
A
Provide glucose, amino acids, and sometimes triglycerides through a gastric or jejunal tube. Amino acids go into the TCA cycle.
22
Q
Pyruvate –> OAA in gluconeogenesis what needs to be carboxylated?
A
Enzyme – Biotion - CO2
23
Q
Phosphorylated phosphofructokinase 2
Phosphorylated Fructose 2,6 Bisphosphatase
A
inhibits F6P to F2,6 Bisphosphate
Stimulates F2,6 Bisphosphatase to F6P
24
Q
Fructose 2,6 Bisphosphate inhibits and stimulates what?
A
Inhibits F1,6Bisphosphatase
Stimulates Phosphofructokinase
25
Fructose 1,6 Bisphosphatase is inhibited by and stimulated by?
Inhibited by F 1,6 Bisphosphate and AMP
| Stimulated by citrate
26
How does glucagon inhibit and stimulate steps in F2,6 Bisphosphatase? What is the overall downstream affect on gluconeogenesis and glycolysis?
By phosphorylation of F 2,6, Bisphosphatase and Phosphofructokinase 2. Downstream it activates gluconeogenesis and inhibits glycolysis
27
Complete the following rxns
Glycolysis: F6P + + -- --> F1,6BP +
Gluconeogenesis: OAA + GTP -- PEP carboxykinase -->
F1,6 Bisphosphate + - F1,6Bisphosphatase->
G6P + -- G6Phosphatase-->
Mg2+, ATP -- PhosphofructoKinase 1 --> ADP
--> GDP + CO2 + PEP
H20 -- F1,6Bisphosphatase--> F6P + Pi
H2O --> Glucose + Pi
28
Galactose is phosphorylated on the 1 position by the action of the enzyme
galactokinase
29
If galctokinase is missing what happens to galactose and thereafter?
If the transferase is missing, the condition also results
galactose is partially excreted, but it also accumulates and leads to formation of cataracts through reduction to the corresponding hexitol, called either galactitol or dulcitol.
galactosemia.
30
The clinical manifestations consist of issues of galctose metabolism...
nutritional failure, enlargement of the liver and spleen, cataracts and mental retardation.
31
The major laboratory findings are (for issues of galactose metabolism)
galactosuria, amino aciduria, albuminuria and an impaired galactose tolerance.
32
The major linkage between glucosyl residues are ____ with branch points in the chain which are _____ and occur at an average spacing of _____
α1 --> 4
α1 --> 6
8-12 α1 --> 4
33
Higher values can be obtained on a high carbohydrate diet and after ____ hrs only traces are found
24- 48 hrs
34
Liver has __% glycogen content and muscle has __% and brain
5% and 0.5-1% and 0.1%
| Brain relies almost entirely on glucose supply
35
Lactose is a dissacharide of galactose and gluose linked by a beta 1-4 glycosidic link. Is lactose absorbed from the intestine?
beta 1-4 glycosidic link and No it has to undergo hydrolysis into galactose and glucose.
36
Classic Galactosemia
-Uridyltransferase deficiency
-Autosomal recessive
-causes galactosemia and galactosuria, vomiting, diarrhea, and jaundice
-accumulation of galactose 1-phosphate and galactitol in nerve, lens, liver, and kidney tissue causes liver daage, severe mental retardation, and cataracts
-antenatal diagnosis is by CVS. New born screening is available
- Therapy: Rapid Dx and removal of galactose (lactose) from the diet
-Despite adequate treatment , at risk for developmental delays and, in females, premature ovarian failure
-
37
Galactokinase deficiency and what happens if galactosemia is persistent?
- rare autosomal disorder
- Galactosemia and galactosuria
- Causes galactitol accumulation if galactose present in diet
A: Aldose reductase is present in liver, kidney, retina, lens, nerve, tissue, seminal vesicles, and ovaries. Under conditions of galactosemia the elevated galactitol can cause CATARACTS!
38
Glycogen is less readily depleted in muscle. Why?
In total it has the most glycogen storage but does not have G6Phosphatase to convert to Glucose and release into blood. Instead muscle will use G6P for energy.
39
What two hormones cause the degradation of glycogen?
Epinephrine and glucagon
40
Binding of epinephrine and glucagon to cell membrane receptors activates ___ and increases ____. This is followed by the activation of (Enzyme). This enzyme catalyzes the phosphorylation of ____ and ______. The latter ___ catalyzes the phosphorylation of ____ to ______. This process is reversed by ____ which catalyzes the removal of phosphate group from ___
1. enzyme adenyl cyclase
2. the formation of cyclic AMP
3. cyclic AMP sensitive protein kinase.
4. glycogen synthase (inactivation)
5. phosphorylase kinase (activation)
6. phosphorylase b to active phosphorylase a.
7. phosphoprotein phosphate
8. glycogen synthase b (activation) and glycogen phosphorylase a (inactiva-tion).
41
Liver uses what hormone for glycogen metabolism regulation. Muscle uses two hormones
1. glucagon
| 2. glucagon and epinephrine
42
Many hereditary storage diseases involve defects in?
degradation
43
Type 1a Storage Disease
Defect in G6Phosphatase, increased G6P induces Glycogen synthase by activating glycogen synthase b (which needs to be de phosphorylated to become active). Liver and kidney affected. Hypoglycemia, lactic acidosis, short stature, enlarged liver due to glycogen accumulation, ketosis.
44
Type 1b Storage Disease
Translocase deficiency. G6Phosphatase is made but cannot be translocated out of the ER. Affects liver, kidney, intestine, severe fasting hypoglycemia, fatty liver, hepatomegaly, progressive renal disease, growth retardation and delayed puberty, hyperlacticacidemia and hyperuricemia.
TX: Nocturnal glucose gastric infusions or uncooked cornstarch
45
Type II Storage Disease
Pompe Disease (Rapidly Fatal) . Defected lysosomal enzyme Alpha glucosidase which can split glucose from glycogen. Normal Glycogen. General organs involved. Enlarged HEART and CARDIORESP failure.
46
Type III
Cori. Defect of glycogen debranching enzyme. Causes short outer chains on fasting. Generalized organs involved. Enlarged liver, moderate hypoglycemia, acidosis.
47
Type IV Glycogen Storage Disease
```
ANDERSEN DISEASE
Enzyme Defect: Glycogen branching enzyme
•Glycogen structure: Few branch points
•Organs involved:Generalized
•Characteristics: Cirrhosis, progressive liver failure
```
48
Type V similar to Type VIII
Enzyme Defect: Muscle glycogen phosphorylase
•Glycogen structure:Normal
•Organs involved: Skeletal muscle
•Characteristics:Muscle cramps on exercise
•Similar symptoms are seen in glycogen storage disease type VII in which there is decreased activity of phosphofructokinase activity in muscle
49
Type VI
HERS DISEASE (X-linked recessive)
Enzyme Defect: Liver glycogen phosphorylase
•Glycogen structure:Normal
•Organs involved:liver
•Characteristics: Enlarged liver, moderate hypoglycemia and mild acidosis
•A deficiency of liver glycogen phosphorylase kinase has been classified as either Type VIII or included in Type VI. This condition is X-linked unlike the other glycogen storage diseases that have an autosomal recessive inheritance.
50
Glycerol phosphate shuttle does what? For what tissue types? and what is the redox pair formed during this shuttle?
Sends reducing equivalents of cytosolic NADH to matrix FAD. Certain muscle and nerve cells. DHAP and glycerol3P form a redox pair.
51
Malate Aspartate shuttle does what? For what tissue types? and what is the redox pair formed during this shuttle?
Transfers electrons from cytosolic NADH to matrix NAD. Liver, heart and other tissues. Malate and OAA for the redox pair.
52
What type of reaction get complex molecules to break down into their building blocks that ultimately go into the TCA cycle via acetyl CoA?
Hydrolysis
53
What is the coenzyme of Pyruvate decarboxylase?
Thiamine pyrophosphate
54
Hydroxy ethyl intermediate- TPP is oxidized, how?
It gets transferred onto an oxidized (disulfide form) of lipoic acid which is COVALENTLY attached to E2 Dihydrolipoyl transacetylase.
55
The oxidized hydoxy ethyl intermediate- lipoic acid becomes acetyl coA and reduced sulfhydryl lipoic acid, how?
The acetyl group (bound as a thioester to lipoic acid) is released from lipoic acid and is attached to SH-CoA.
56
How is sulfhydryl lipoic acid reoxidized?
Sulfhydryl lipoic acid is reoxidized by E3 FAD-Dependent Dihydrolipoyl Dehydrogenase. FAD (Flavoprotien) is reduced to FADH2. FADH2 is reoxidized by E3 Dihydrolipoyl Dehydrogenase causing NAD+ to become NADH.
57
1. What inactivates Pyruvate DH complex directly? What activates Pyruvate DH complex (from inactivation) directly and name it's positive regulator?
2. What is a negative/positive regulator of protein kinase?
3. What gives a negative feedback control to Active Pyruvate DH?
1. Phosphorylation by protein kinase, Dephosphorylation by Phosphoprotein phosphatase via hydrolysis; Ca2+
2. Negative: acetyl CoA, NADH, ATP
Positive: CoA, NAD+, pyruvate
3. NADH and acetyl CoA
58
1. Pyruvate DH complex inhibited by?
2. Citrate synthase inhbited by?
3. Isocitrate DH inhibited/activated by?
4. alpha ketoglutarate DH complex inhibited?
1. ATP, NADH, Acetyl CoA
2. ATP
3. ATP, NADH / ADP
4. NADH, Succinyl CoA
59
In TCA cycle which three intermediates serve as intermediates for biosynthesis. There's a fourth that professor Li may not consider
1. alpha ketoglutarate --> glutamate and other a.a, purines
2. Succinyl CoA --> Heme, cholorphyll
3. OAA --> aspartate and other a.a, purines, pyrimidines
4. citrate --> fatty acids, cholesterol
60
High levels of pyruvate carboxylase are found where and what term defines a rxn forming intermediates for a metabolic pathway?
Liver and kidneys. Anaplerosis. It's important to upkeep the production of OAA. Thus other tissue types have this reaction as well just lower occurrence.
61
How are gliomas and acute myelocytic leukemia related to mutations in the TCA cycle?
Isocitrate DH 1 & 2 can be mutated causing the formation of 2-Hydroxyglutarate (2HG). Thus Alpha-ketoglutarate dependent Dioxygenases are competitvely inhibited by 2HG.
This is an issue because Dioxygenases play a rold in demethylating histones and DNA. Thus hypermethylation is found in gliomas and acute myelocytic leukemia.
62
What enzyme is used in the Glycerol Phosphate Shunt? Explain what happens (What intermediates get reduced/oxidized) and the result of the shunt in terms of possible energy production
Glycerophosphate DH. DHAP gets reduced by cytosolic glycerolphosphate DH to glycerol 3 phosphate by NADH. Inside matrix Glycerol 3 phosphate gets oxidized to DHAP by FAD. FADH2 goes into ETC in complex II thus loses about 1 potential ATP.
63
Name the players of Malate-Aspartate shuttle
OAA to Malate via cyt. Malate DH and vice versa in matrix. In matrix OAA + Glutamate --- aminotransferase--> alpha ketoglutarate + Aspartate and vice versa once in cytosol producing once again Glutamate and OAA. Glutamate can pass freely back into matrix. NADH is equivalently turned back into NADH in the mitchondria!
64
Patients who inherit defects in ETC or OX-Phosphorylation exhibit (3) signs. Give two examples of (mostly nuclear gene inheritance)
Myopathy, encelopathy (nerve pathology), lactic acidosis.
Leigh syndrome and Leber hereditary optic neuropathy
65
What percentage of TOTAL ATP in the body is made by Oxidative phosphorylation (ETC)?
Over 80%
66
Define reduction potential. Change of reduction potential (E) is favorable when?
The potential of a redox rxn to accept electrons. Electrons flow from low to high reduction potential. When it is greater than zero.
67
Write down relationship between free energy and reduction potential.
delta G = -nF deltaE
68
What alternate electron donors participate besides NADH from glycolysis, pyruvate D.H complexTCA cycle, and malate-aspartate shuttle?
Glycerophosphate shuttle and fatty acyl CoA D.H. Both provide FADH2 to complex II (Succinate D.H)
69
What inhibits the Translocase of ETC?
atractyloside (a plant glycoside) will inhibit ATP synthesis
70
How many "n" electrons are donated by NADH and FADH2 each?
For both it's 2
71
Delta G standard for ATP Hydrolysis is?
7300 calories. We can use this to divide our delta G for something by and estimate our expected ATP production. But of course it is not 100% efficient and so we know that some of that reduction potential is lost to uncoupling proteins normally expressed thus released as heat energy.
72
Which complexes have Fe-S
| And name all four complexes.
Complex I-II-III.... NADH reductase, Succinate reductase, and Cytochrome C reductase.
Cytochrome C oxidase (IV)
73
Name the inhibitors of Oxidative phosphorylation
Complex 1- Rotenone and Amytal
Complex III- Antimycin A
Complex IV- Cyanide, CO, Sodium Azide (Prevents the use of O2 thus O2 reduction is inhibited) Sodium Azide is used experimentally when sterilizing sample and don't want to use autoclave.
Complex V- Oligomycin
Transporter (Translocase "ANTIPORTER")- atractyloside
74
Thermogenin also called?
Uncoupling protein 1 and is found in the mitochondria of brown fat.
75
Variables affecting ATP output in general
1. Aerobic vs Anerobic
| 2. Electron shuttles (cytosol to matrix)
76
Complete oxidation of one molecule of Glucose: Complete breakdown of ATP, NADH, FADH2, GTP => how many ATP?
10NADH, 2FADH2, 2GTP, 2ATP ==> 30-38 ATP
77
ROS formation/defect in formation can lead to what? How can ROS be formed?
aging, carcinogenesis
Defect in formation --> chronic granulomatous diseases
Impaired metabolism --> ALS
respiratory chain leak (CoQ), radiation, in VERY long chain fatty acid metabolism in peroxisomes the FADH2 formed is oxidized with the formation of hydrogen
peroxide
78
Macrophages and nuetrophils both have what enzyme? Neutrophils is special why?
NADPH oxidase
| Myeloperoxidase
79
How can a peroxyl radical form of a fatty acid chain?
| What can be formed due to this?
ROS remove hydrogen ion (proton) from fatty acid chain leaving a carbon radical which reacts with O2 and form C- O-O(radical). The peroxyl can then steal a hydrogen from a nearby chain and the cascade continues until two radicals pair.
Damage of membrane can lead to lipofuscin formation. Lysosomal degradation of lipid (granular brown yellow which typically indicate aging cells)
80
define granuloma. What chromosome is the mutated genes for one of the subunits on? However neutrophils of Women show what percentage of disease incidence and why?
Persistent next of infected cells. This can arise when the gene for NADPH oxidase is defected. People with Chronic Granulomatous Disease have difficulty ridding themselves of bacateria esp. that have catalase for protection.
X chromosome thus mostly men affected. Women who are carriers 50% are affected due to variable X-inactivation.
81
ALS (Motor fxn diminished without loss of cognitive fxn- Prof. Hawking, onset in mid life death within 1-5 years): Two types describe the mutation. And what is the inheritance?
Mutations in the SOD1 gene, whose product is CuZnSOD, are associated with around 20% of familial ALS cases and comprise a significant known cause of ALS. There are two general categories of ALS mutant CuZnSOD proteins: “wild-type-like” mutants, which have similar levels of metal ion levels to wild type CuZnSOD, and “metal-binding-region” mutants, which include mutations in the metal binding ligands themselves or with regions associated with metal binding.
Evidence supports the claim that SOD1 mutations are inherited in an Autosomal Dominant manner in fALS and induce a gain of CuZnSOD function. This mechanism is currently unknown.
82
ROS Formation with NADPH oxidase and myeloperoxidase
```
NADPH oxidase(in both type of phagocytes)
2 O2 +NADPH -> 2 O2•-+ NADP++ H+
```
•myeloperoxidase(in neutrophils only)
H2O2+ Cl-->OCl-+ H2O
83
Xanthine oxidase makes what?
Hypoxanthine --> xanthine, superoxide (O2 anion radical)
84
Draw Xanthine Oxidase and UQ10 rxn with O2. Superoxide attack onto aconitase and the lead into a fenton reaction.
Fe2+ + H2O2 --> Fe3+ + OH (radical) + OH-
85
List all 6 antioxidants
Alpha-tocopherol (Vit. E) which removes covalent links between ROS in FA lipd membranes (e.g. ETC). Bilirubin,, Reduced Glutathione, Vit. C (Under right dosage), uric acid, beta carotene.
86
Why do the thyroid gland need to form hydrogen peroxide (H2O2)?
H2O2 is needed to add Iodine to thyroglobulin to make thyroxine.
87
Bacteria are engulfed into what which fuses with what?
In bacteria and neutrophils what catalyzes the production of superoxide and explain the difference that occurs in neutrophils.
Phagosome, lysosome
NADPH oxidase--> superoxide --> SOD---> Hydrogen peroxide. But some bacteria have enough catalase to protect themselves thus neutrophils can take the hydrogen peroxide + Chloride ions to make a strong antiseptic Hypoclorite ion.
88
A special superoxide can be used to mediate tumoricidal and bactericidal actions of macrophages. Explain the parts to this rxn.
NO is made by arginine --> citrulline. NO synthase is the catalyst. NADPH is oxidized to NADP+ and Oxygen become NO
89
two forms of ALS caused by protein misfolded aggregates (inclusions)
fALS and sALS (more common)
90
Hemolytic anemia connected with G6PDH deficiency. Draw out the reaction completely. What oxidative stressor induce the hemolysis due to this deficiency? What is mode of inheritance?
```
G6P needs to be oxidized to 6 Phosphogluconate which goes in HMP Pathway and then glycolysis.
Hydrogen peroxide (oxidative) stress includes infection, flava beans, and certain drugs. X-Linked recessive.
```
91
Two functions of HMP shunt:
| What happens to excess ribose5P for nucleic acid synthesis
1: provide NADPH for FA synthesis and reduction of Glutathione
2. Provide ribose-P for nucleic acid synthesis
Gets converted into glycolytic intermediates
92
Pentose Phosphates and Photosynthesis
In plants the enzyme phosphoribulose kinase catalyzes the phosphorylation of ribulose 5-phosphate to form ribulose 1,5-bisphosphate. In the Calvin cycle, CO2 is fixed in the reaction catalyzed by the enzyme ribulose 1,5-bisphosphate carboxylase as follows:
Ribulose 1,5-bisphosphate + CO2 ----> 2 molecules of 3-phosphoglycerate
93
Fructose Metabolism and the lack of ALDOSE?!
Fructose is obtained from sucrose in the diet. Non-specific hexokinases will catalyze the phosphorylation of fructose on the 6 position:
fructose + ATP ----> fructose 6-phosphate + ADP
A more specific ketohexokinase called fructokinase catalyzes the phosphorylation of fructose on the 1 position. This enzyme is the one chiefly responsible for phosphorylation of fructose in mammals. A deficiency of fructokinase causes fructosuria which is an asymptomatic condition. However, a lack of the fructose 1-phosphate ALDOLASE results in fructose intolerance. There is an accumulation of fructose 1-phosphate and a resulting vomiting, loss of appetite, hypoglycemia and acidosis. Fructose or sucrose should be avoided in the diet.
Fructose occurs in semen and is formed in the seminal vesicles from glucose by reduction to sorbitol and oxidation of the sorbitol to fructose.
94
How many molecules of glucose are needed in the HMP shunt to get glycolytic intermediates and what are these intermediates?
3 molecules of glucose
| 3PGAL and F6P
95
What glycolytic intermediates can form R5P?
F6P and 3PGAL
96
Name all the enzymes used in Pentose phosphate shunt and the products that are useful for different pathways.
G6PDH deficiency gives resistance to?
G6PDH&phosphgluconolactone hydrolase, 6phosphogluconate DH, R5P isomerase, phosphopentose epimerase, transketolase (2), transaldolase (3)
NADPH for FA synthesis and reduce Glutathione
3PGAL x 2 and F6P for glycolytic intermediates
R5P for nucleic acid synthesis. Once satisfied it will be used for the production of glycolytic intermediates.
Malaria
97
Difference between Essential Fructosuria and Hereditary Fructose Intolerance. How do we get fructose?
BOTH AUTOSOMAL RECESSIVE!
1. Lack of Fructokianse, Fructose accumulates in urine, asymptomatic- benign
2. Lack of Aldolas B which traps F1P and causes severe hypoglycemia, vomiting, jaundice due to impaired conjugation of bilirubin, hemorrhage, hepatomegaly, hyperuricemia. Can cause hepatic failure and DEATH! TX: Rapid removal of fructose and sucrose from diet.
3. Sucrose --> Glucose + Fructose
4. Normally GAL gets further broken down into glycerol P and enters glycolysis by glycerol P DH DHAP triose phosphate isomerase --> 3PGAL.
98
Which has short chains of saccharide attached to the protein, proteoglycan or glycoproteins?
Proteoglycan has longer (polysaccharide) chains, associated with extracellular stucture. Proteoglycans are usually structural components of the extracellular
matrix. Some have a lubricant role. Heparin is normally intracellular. It inhibits blood clotting.
Glycoproteins has shorter (oligosacchiride) chains. Glycoproteins have a variety of fxns:
1. Structural moleculeCollagens
2. LubricantMucins
3. Transport moleculee.g. Transferrin,
Ceruloplasmin
4. Immune systemImmunoglobulins,
Histocompatibility antigens,
Blood group determinants
5. Hormonee.g. HCG, TSH
6. Enzymese.g. Alkaline phosphatase
7. Blood clottinge.g. Fibrinogen
8. Cell surface recognitionLectins
99
Structure of glycoprotein:
| Difference between O-glycosidic link and N-glycosidic link.
!!!!!There may be one or more carbohydrate chains covalently linked to a protein. The chains may be neutral or negatively charged. They are frequently branched.!!!!
1. In collagen there is an O-glycosidic link between galactose or glucose and the hydroxyl group of hydroxylysine.
Other O-linked glycoproteins have a glycosidic link between N-acetyl galactosamine and either serine or threonine e.g. blood group substances and salivary mucins.
2. N-glycosidic links exist between N-acetylglucosamine and asparagine. There are two types:
A. High mannose
B. Complex. For example, in addition to mannose they may contain N-acetylglucosamine, galactose, fucose and N-acetylneuraminic acid (sialic acid)
100
Define I-cell Disease (Mucolipidosis II). What goes awfully wrong in infants? Fibroblasts look like what in this disease?
The hyrdolase (lysosomal) enzymes lack the targeting signal of mannose-6-phosphate. Thus indigestible substrates accumulate in lysosomes and cause infantile death! Have dense inclusion bodies
101
Clinical Characteristics of Mucolipidosis II (I-cell disease)
severe dysostosis (disorder in bone ossification), mental retardation, hepato- and cardiomegaly, recurrent upper respiratory infections, umbilical hernia, diastasis recti (gap of >2.7 cm between the two sides of rectus abdominus).
102
Proteoglycan resembles what in life? The core protein is covently linked to what? Name some characteristics of it.
Bottle brush and glycoaminoglycan. The glycosaminoglycan typically consists of a long polysaccharide chain with a repeating disaccharide motif..
Glycosaminoglycans are polyanionic. The negative charge comes from the presence of carboxyl and/or sulfate groups. The carboxyl group is on either D-glucuronic acid or its epimer L-iduronic acid.
•The repeating disaccharide is glycosidically linked to a serine residue on the protein through a galactose-galactose-xylose-serine sequence.
103
The glycosaminoglycans include and are characterized by what?:
•Hyaluronic acid, Chondroitin sulfate, Dermatan sulfate, Heparan sulfate, Heparin, Keratan sulfate
Polysaccharide chains
Repeating disaccharide motifs
Amino groups
Polyanionic character due to carboxyl and/or sulfate groups
104
Synthesis of glycoproteins and proteoglycans
•The units in the saccharide chains are added from nucleoside diphosphate derivatives e.g.
UDP-glucuronic acid, UDP-N-acetylgalactosamine and GDP-mannose. Sialic acid in glycoproteins is
added from CMP-NANA. These additions are catalyzed by specific glycosyltransferases.
•For glycosaminoglycan synthesis and synthesis of O-linked glycoproteins, the addition is direct.
•For N-linked glycoproteins, the chain is formed on dolichol pyrophosphate and then transferred to the protein.
105
Degradation of glycosaminoglycans and gycoproteins
Hydrolytic lysosomal enzymes act on the ends of the chains on a last-on-first-off basis.
106
Another word for glycoaminoglycans. Diseases of theses are almost always due to defective lysosomal hydrolytic enzymes. What is the pattern of inheritances of these diseases and usually what are the phenotypic characterics?
The mucopolysaccharidoses are a series of hereditary diseases resulting from mutations in genes coding for degradative enzymes acting on glycosaminoglycans (mucopolysaccharides).
mucopolysaccharide. Usually autosomal recessive except X-Linked Hunter syndrome (MCPSII). Affected individuals have mental retardation and/or structural deformity.
107
MPS I
Hurler, defect alpha-L-iduronidase, accumulate dermatan sulfate and heparan sulfate, and features clouding of cornea and mental retardation
108
MPS II
X-linked Hunter Syndrome, defect in iduronate sulfatase, accumulate dermatan sulfate and heparan sulfate, no clouding of cornea, milder course than in MPS I.
109
MPS IIIA
Deficiency in one of four degradative enzymes
Sanfillipo syndrome A, defect in heparan and N-sulfamidas, accumulate heparan sulfate, and mild somatic but severe CNS effects
110
MPS IIIB
Deficiency in one of four degradative enzymes
Sanfillipo syndrome B, defect in Nacetyl-alpha-D-glucosamindase, accumulate Heparan sulfate, clinical features same as MPS IIIA.
111
MPS IV
Morquio syndrome, defect in hexosamine 6-sulfatase (deficiency of galactose-6-sulfatase or beta-galactosidase), accumulate keratan sulfate, normal intelligence, sever bone changes, cloudy cornea
112
MPS VI
Maroteaux Lamy Syndrome, defect in Arylsulfatase B (N-acetylgalactosamine 4-sulfatase), accumulate dermatan sulfate, sever bone, soft tissue and corneal change.
113
Define difference in role of digestion with segments of small intestine
duoedenum for chemical digestion --> receives the chyme from stomach. Jejunum absorbs nutrients, minerals, and vitamins from intestine to blood. Illeum absorbs vit. B12 and reabsorption of bile salts
114
What breaks down dietary lipids in the gut lumen?
Occurs in jejunum and pancreatic lipase (hydrolytic) turns a TAG into a FA and a monoacylglycerol or diacylglycerol.
115
What is the only committed step in TAG synthesis within an enterocyte?
1,2-diacylglycerol acyltransferase (DGAT) w/ Acyl-CoA. TAG is reassembled inside the enterocyte and with proteins and other lipids convert to a chylomicron. Monoacylglycerols, diacylglycerols, and FA can cross the intestinal lumen.
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Orlistate (Xenical)
| Lovaza
does not allow for the absorption of TAG by blocking gastric and pancreatic lipases thus you get less absorption and digestion ~ 30% fat uptake.
Promotes of lowering plasma TAG levels possibly by inhibiting 1.2-diacylglycerol acyltransferase (DGAT), reduces TAG synthesis in liver and increases beta oxidation of TAG.
117
Short, medium, long chain FATTY ACIDS
12 e.g. palmitic acid (saturated) is 16 C
118
Two essential FATTY ACIDS are? and provide examples of sources for both.
linoleic acid and alpha-linoleic acid, the rest of FA are synthesized de novo. Linoleic acid (omega-6) is precursor for arachidonic acid. Alpha linoleic (omega-3) precursor for omega-3 fatty acids
Linoleic acid- oils from safflower, grape seed, poppyseed, sunflower, corn, wheat germ, cottonseed, soybean, walnut
Alpha-linoleic acid- kiwi seeds, flax, soybean, broad green leaves
119
What do we need for de novo synthesis of Fatty acids? And where does it occur.
We need NADPH, ATP, acetyl CoA for 2-Carbon sources has a reactive sulfhydryl group. It occurs mostly in the cytosol of liver but less commonly can occur from mobilizing lipids from adipose tissue.
120
How do we shuttle the necessary acetyl CoA from m.t matrix to cytosol?
We have a citrate shuttle
121
Draw out citrate shuttle. why is it needed?
Because acetyl CoA made in matrix cannot cross inner mt membrane. Convert Acetyl CoA + OAA into citrate by citrate synthase and citrate once in cytosol gets converted back to OAA + acetyl CoA by ATP-citrate lyase and CoA.
122
What enzyme gets cytosolic acetyl CoA into malonyl CoA? What are the three regulators to this?
Acetyl CoA carboxylase. This is FA synthesis rate limiting step. 1. allosteric regulation, 2. phosphorylation and hormonal 3. dietary intake regulation.
123
Allosteric regulation of de novo FA synthesis rate limiting step. what is characteristic of the active enzyme?
citrate (+), long chain FA >12C (-).....like palmitic acid (16C) of Acetyl CoA carboxylase. To be active Acetyl CoA carboxylase (the grey beads) must polymerize into an active dimer.
124
Describe hormonal/phosphorylation control of FA synthesis via the rate limiting step. talk about the upregulation.
Acetyl CoA carboxylase is inhibited by phosphorylation via AMP activated kinase (AMPK) and dephosphorylation via protein phosphatase.
Upregulation of AMP activated kinase by glucagon, and low cell energy. Upregulation of protein phosphatase by insulin and increased blood glucose uptake into cell.
Low energy, glucagon we want to break down FA not build up thus we which to phosphorylate acetyl CoA carboyxlase (non-polymer) to inactive de novo FA synthesis. Vice versa if we have insulin and increased glucose uptake ok fine let's make some FA(s) by dephosphorylating the acetyl CoA carboxylase and get acetyl CoA into malonyl CoA.
125
how does diet affect FA synthesis and what specifically does it affect?
High caloric diet increase synthesis of Acetyl CoA carobyxlase. Low caloric diet decreased synthesis of Acetyl CoA carboxylase.
126
Explain the characteristics of FAS (Fatty acid synthase)
a dimeric enzyme in the cytosol with 7 different ezymatic functions. It has multiple domains and catalyzes the elongation of fatty acids. The main FA made is palmitic acid (16C) and other FA are a modification of palmitic acid. Synthesis begins on the methyl end.
127
Draw out fatty acid synthase reaction to go from acetyl CoA + malonyl CoA --> Palmitic acid
1 acetyl CoA, 7malonyl CoA, 14NADPH, 14 H+ ---> 8CoA, 14 NADP+, 7CO2, 7H2O, 1 palmitic acid
128
reasons for fatty acid oxidation (4)
Cardiac contractility, starvation, diabetics w/ low blood glucose, prolonged bioenergetic exertion
129
Fuel reserve and energy needs for 160 lb man/woman
130,000 kcal fat, 24,000 kcal protein, 1,600 kcal glycogen in liver and muscle. 2,000-2500 kcal per day. Fat reserve can last for 2 months.
130
What happens once FA comes to a cell?
FA needs to be activated and transported to mitochondria for beta oxidation. We get the formation and utilization of ketone bodies to make acetyl CoA to go into TCA cycle.
131
How does FA get mobilized from an adipose cell? what simulates/inhibit?
Hormonal regulation (+ epi, glucagon, adrenocorticotropic hormones / - insulin) which actives the G-protein coupled receptor. Cascade follows with adenylate cyclase getting ATP--> cAMP which activates PKA and active PKA activates triacylglycerol lipase by phosphorylation. This breakes up TAG into DAG and further lipases separate out glycerol and thus FA is able to leave cell via albumin. Both are released into extracellular space.
132
Most of ATP in a well fed person comes from? What needs to happen for long chain FA to enter mitochondrai and where does beta oxidation occur (what tissue type)?
FA oxidation. Carnitine shuttle short and and medium diffuse fine. Inside liver.
133
What is the rate limiting step in carnitine shuttle? and what inhibits it?
carnitine palmitoyl-transferase 1 can be inhibited by malonyl CoA. The CoA on a fatty acyl is the issue. This we transfer a carnitine in place of the CoA. The fatty acyl-carnitine enters the matrix. Carnitine is replaced by CoA and becomes activated Fatty acyl CoA and carnitine can diffuse back into innermembrane space via a translocase.
134
How many carbons are added/removed during Fatty acid metabolism?
two at a time. Thus during beta-fatty oxidation produces an FADH2, NADPH, and acetyl CoA (one of each and in this order). remember acetyl CoA is a two carbon molecule.
Removal of carbons follows the rule of last one on last one off. The carbons last on are the ones closest to the carboxyl group.
135
Final total for beta oxidation of palmitic acid
7FADH2, 7NADH, 8 acetyl CoA,
8 acetyl CoA provide 12 ATP each acetyl CoA in TCA cycle
this 17 ATP + 21ATP+ 96ATP = 131 ATP.... The Acetyl CoA, FADH2 and NADH go into TCA cycle and ETC.
136
Difference of transport between short/medium and long chain FA?
Directly absorbed and attached to Albumin from intestine (jejunum) vs packaged into chylomicrons
137
Ketone bodies
acetone, acetoacetic acid, and beta-hydroxybutyric acid
produced in liver in mitochondrial matrix
• produce during starvation when fatty acids are mobilized
from adipose tissue
• produced when acetyl CoA exceeds the capacity of TCA
cycle
• because they are soluble, no need to bind albumin (in contrast
to fatty acids)
• crucial sources of energy for brain, skeletal/cardiac muscle,
intestinal mucosa, renal cortex
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Leptin
encoded by the obese (Ob) gene
• secreted by adipocytes
• regulates food intake
• inhibits hunger, binds receptors in hypothalamus!
• prevents lipid accumulation in non-adipose tissues
• regulates energy metabolism
• stimulates uptake of glucose
• stimulates AMP kinase, inhibiting fatty acid synthesis
• stimulates fatty acid oxidation
139
```
CCK
Ghrelin
Insulin
Glucagon
GLP1 (Glucagon-like peptide 1)
```
```
1. suppresses
hunger, secreted in duodenum,
stimulates release of digestive enzymes
by pancreas and gallbladder
2. stimulates hunger
secreted by stomach and
pancreas, binds to receptors in
the pituitary.
3. increases glucose
uptake, and storage of glucose as
glycogen in the liver and muscle,
secreted by pancreas.
4. increases blood
glucose levels, secreted by
pancreas.
5. increases insulin, decreases
glucagon, increases satiety,
secreted by L cells in the ileum.
```
140
What happens to patients with Type II Diabetes that have Roux-en-Y bypass?
Remission of Type II Diabetes
