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Medical Biochemistry > Enzymes/Coenzymes/Inhibitors/Activators > Flashcards

Enzymes/Coenzymes/Inhibitors/Activators Flashcards

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0
Q

Other name for Acetyl CoA

A

Pantothenic Acid

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1
Q

Hydrophilic carboxyl group of Facid. Ionized at what pH

A

pH 7

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2
Q

Substrates/Products Citrate Synthase

A

Substrate: OAA + Acetyl Coa
Products: Citrate & Coa

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3
Q

Substrate/Products/Coenzymes ATP-citrate lyase

A

Substrate: Citrate & ATP & Coa
Products: OAA & Acetyl Coa & ADP+Pi

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4
Q

Prosthetic of ACC

A

Biotin. & Adds CO2 to methyl end of Acetyl CoA

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5
Q

Acetyl Coa Carboxylase: Substrate/Products

A

Substrate: Acetyl Coa & ATP & Co2
Products: Malonyl & ADP + Pi

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6
Q

Short-term allosteric regulation of acetyl CoA carboxylase

A

Citrate shifts the polymer - dimer equilibrium towards polymer formation. Activation

Palmitoyl CoA shifts the equilibrium towards dimer formation. Inhibition

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7
Q

Short-term hormonal regulation of acetyl CoA carboxylase

A

Glucagon, epinephrine, and norepinephrine trigger a cAMP dependent phosphorylation of the enzyme (through activation of AMPK) that shifts the equilibrium towards dimer formation (inactive form).

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8
Q

Long-term regulation of acetyl CoA carboxylase

A
  • high carbohydrate and fat-free diets lead to increased synthesis of ACC (up-regulation, induction) resulting in increased synthesis of FA
  • high-fat diets, fasting and glucagon lead to decreased synthesis (down-regulation, repression) resulting in decreased synthesis of FA
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9
Q

Enzyme the hydrolyse Palmitoyl-ACP in order to form free Palmitoyl

A

Thioesterase

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10
Q

Activation Fatty Acid: Substrates, Products, Enzymes

A

Substrates: Fatty Acid + CoASH + 2ATPs
Enzyme: Fatty Acyl Coa Synthetase
Products: Fatty Acyl Coa + AMP + PPi(–>2Pi)

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11
Q

Systemic fatty acid oxidation disorders

Organs, Symptoms, Causes

A

Organs: Liver, Muscle
Symptoms: Hypoglycemia, Hypoketosis
Cause: MCAD deficiency, Carnitine deficiency, CPT-1 deficiency(liver isozyme), Jamaican vomiting sickness

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12
Q

Myopathies fatty acid oxidation disorders

Organs, Symptoms, Cause

A

Organs: Muscle cardiac & skeletal
Symptoms: Muscle cramps during exercise
Cause: Myopathic Carnitine deficiency, CPT-2 deficiency

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13
Q

RLE of Cholesterol Synthesis

A

HMG CoA Reductase

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14
Q

HMG CoA Reductase: Substrate/Products

A

Substrate: HMG CoA (6C) + 2NADPH
Products: Mevalonate (6C) + 2NADP+ + CoA

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15
Q

Inhibitors/Activators HMG Coa Reductase

A

Inhibitors:
Glucagon
Cholesterol
Statin Drugs: Zocor, Lipitor

Activators: Insulin

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16
Q

How does AMP Kinase regulate HMG CoA Reductase

A

• Sterol-Independent Regulation of HMG- CoA Reductase
• High intracellular concentrations of AMP stimulate AMP Kinase which phosphorylates HMG-CoA and inactivates it
• Dephosphorylation by a phosphoprotein phosphatase (activated by insulin) activates HMG –CoA

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17
Q

Upregulation of HMG CoA reductase?

A
  • The amount of HMG CoA reductase enzyme is regulated by intracellular (cytosolic) concentrations of Cholesterol
  • Low cholestrol stimulates the release of a
    regulatory (SREBP) protein from the ER
  • Sterol regulatory element binding protein
    (SREBP) binds to a region in the HMG CoA reductase gene called sterol responsive element (SRE) resulting in increased transcription of the HMG CoA reductase gene and subsequent increase in the amount of HMG CoA reductase.
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18
Q

When does proteolysis of cholesterol occur?

A

High Intracellular cholesterol and/or Mevalonate leads to rapid proteolysis of HMG CoA Reductase enzyme by the ubiquitin system in proteosomes.

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19
Q

SLOS (Smith-Lemli-Opitz Syndrome)

A

A genetic defect of cholesterol synthesis (autosomal recessive)
7-dehydroxycholesterol Reductase, needed for double bond formation in the ring B, is deficient.

Relatively common, leads to microencephaly and other embryological malformations, surviving children have an IQ 20-40

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20
Q

Synthesis of palmitate from Acetyl CoA requires how many ATP and NADHs

A

14 NADPHs & 7 ATPs

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21
Q

Sequence of synthesis of TAGs (Liver & Adipose tissue)

A

DHAP Glycerol phosphate Lysophosphatidic acid Phosphatidic acid(DAG phosphate) Diacylglycerol(DAG) Triacylglycerol (TAG)

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22
Q

Activation Facid(Cytosol): Enzyme/Substrate/Products

A

Enzyme: Fatty Acyl CoA synthetase
Substrate: Fatty acid + CoASH + 2ATP
Products: Fatty Acyl Coa + AMP + PPi

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23
Q

Synthesis of palmitate from Acetyl CoA requires how many ATP and NADHs

Study These Flashcards
A

14 NADPHs & 7 ATPs

24
Sequence of synthesis of TAGs (Liver & Adipose tissue)
DHAP Glycerol phosphate Lysophosphatidic acid Phosphatidic acid(DAG phosphate) Diacylglycerol(DAG) Triacylglycerol (TAG)
25
Coenzyme of Propionyl CoA Carboxylase?
Biotin
26
Coenzyme for Methylmalonyl Coa mutase?
Vit B12
27
Enzyme to form & store cholesteryl esters?
ACAT
28
Enzymes cleaves TAGs in Chylomicrons & VLDL
Lipoprotein lipase
29
Proteins that anchor and activate Lipoprotein Lipase
Anchor: Heparan sulfates Activates: Apo C2
30
Stimulates & Inhibits the reaction: LDL---> OxLDL
Stimulators:Superoxide, NO, Hydrogen peroxide, Other oxidants Inhibitors: Vit E, Ascorbic acid, B-carotene, other antioxidants.
31
Role CETP (cholesteryl ester transfer protein)
Allows transfer the transfer of TAGs from VLDL into HDL in exchange for cholesteryl esters
32
What's so special with HDL
- Potential anti-atherogenic properties + Reverse cholesterol transport using as key players apo A-1, LCAT, plasma membrane ABC-transporter for free cholesterol and CETP + Contains enzymes that reduce LDL oxidation (Paraoxonase and PAF acetylhydrolase) - Potential plaque stabilization properties + HDL-mediated cholesterol efflux reduces plaque lipid content + HDL may reduce plaque macrophage content and their activity and increase plaque smooth muscle content and prevent rupture
33
Malicious Enzyme: Substrates, Products
Substrate: Malate, NADP+ Products: Pyruvate, NADPH + H+
34
Thioesterase: Substrates, Products
Substrates: Palmitoyl-ACP + H2O Products: Palmitate + ACP-SH
35
Required to produce TAG from 2-Monocylglycerol
2 Acyl CoA:monoacylglycerol acyltransferase | & 2 Fatty Acyl-CoA
36
Cholesterol ---> Cholic Acid Enzyme? Inhibitor/Activator?
Cholesterol 7-alpha-hydroxylase (catalyze a the addition of OH group to C-7) Activator: Cholesterol Inhibitor: Cholic Acid
37
Coenzyme for Lead
Zinc
38
Ribose 5-P----> 5-Phosphoribosyl 1 Pyrophosphate (PRPP) | Enzyme, Cofactor, activator/inhibitor
PRPP Synthetase Cofactors: ATP---> AMP & Mg2+ Activator: Pi Inhibitor: Purine nucleotides
39
Committed step of nucleotide synthesis: Enz, Substrate, Products, Cofactors, Activators, Inhibitors
Enz: Glutamine Phosphoribosyl Pyrophosphate Amidotransferase Substrate: 5 Phosphoribosyl 1 Pyrophosphate + Glutamine Products: 5 Phosphoribosylamine + Glutamate Cofactors: Mg2+ Activator: PRPP Inhibitors: AMP, GMP, IMP
40
Pteridine Precursor + Aminobenzoic Acid (PABA) ----> Folic Acid Enzyme, Cofactor, Drug that inhibits
EnzyMe: Dihydropteroate Synthetase Co-factor: ATP, Glutamate Drug: Sulfonamide
41
Dihydrofolate reductase | Substrate/Product, Cofactor, Inhibitor
Substrate: Folic Acid Product: THF acid Co-factor: 2NADPH Inhibitor: Methotrexate
42
Serine hydroxymethyltransferase | Substrate, Product, Cofactor
Substrate: Serine Product: Glycine Co-factor: THF---> N5,N10 Methylenetretrahydrofolate
43
Enzymes that transport bilirubin in liver
- Ligand protein | - Z protein
44
Synthesis of CTP from UTP | Substrate, Products, enzymes, cofactors
Substrate: UTP Product: CTP Enzyme: CTP synthase Cofactor: Glutamine + ATP
45
Ribonucleotide----> Deoxyribonucleotides | Enzyme, activator, inhibitor
Enz: Ribonucleotide di phosphate Reductase Activator: ATP Inhibitors: dATP, hydroxyurea
46
Enzyme salvages pyrimidines
Pyrimidine Phosphoribosylthransferase | PRPP is the source of ribose phosphate
47
Which Prostaglandins are Mediators of Inflammation
PGE2 | PGF2a
48
Precursor for Arachidonic acid
Linolenic acid
50
Eicosapentanoic acid #
20:5 w3 | PG and TX from Omega3
51
Reaction catalyzed by Adenosine Deaminase
Adenosine----> Inosine Release NH3
52
Reactions catalyzed by Purine nucleoside Phosphorylase
Inosine----> Hypoxanthine Guanosine----> Guanine
53
What stimulates Tissue factor pathway inhibitor TFPI | & what is its function?
- Heparin | - Bind and inhibit Factor Xa & Factor VIIa/tissue factor
54
Which is administered first: Warfarin or heparin
Heparin because warfarin is slow acting.
55
What enzyme oxidized cystein to taurine
Cysteine di oxygenate
56
How much ATP required in Purine synthesis?
4 ATP
57
Cholesterol modified by bacteria in intestine to form:
Coprostanol & Cholestanol
58
What increases in Acute Hepatitis and long standing hepatitis?
Acute: ALT level>>>AST levels Long standing alcohol cirrhosis: AST>>>ALT (AST:ALT ratio approx 2:1)

Medical Biochemistry (8 decks)

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