Oxidation and biosynthesis of fatty acids Flashcards
(116 cards)
1
Q
Stages of Fatty Acid Oxidation
A
- Activation of fatty acids
- Transport of Fatty Acyl CoA into the matrix of ` mitochondria
- Degradation to two-carbon fragments
2
Q
Location of activation of fatty acids
A
outer mitochondrial membrane
3
Q
Location of degradation to two carbon fragments
A
mitochondrial matrix
4
Q
Process of Activation of FA
A
- FA are converted to CoA thioesters
- PPi released is hydrolysed
- 2 phosphoanhydride bonds are consumed to activate one FA to a thioester
5
Q
enzyme that catalyzes conversion of FA to CoA thioesters
A
acyl-CoA synthetase
6
Q
enzyme that hydrolyses PPi
A
pyrophosphatase
7
Q
Reaction involved in Step 1 of FA Oxidation
A
FA + ATP Acyl adenylate + PPi
Acyl adenylate + HS—CoA Acyl CoA + AMP
8
Q
Difference of Acyl CoA and Acetyl CoA
A
Acetyl CoA: R = methyl
Acyl CoA: R= Carbon chain of any length; two carbons shorter than Acetyl CoA
9
Q
shuttling system used to transport FA into the mitochondria
A
carnitine shuttle system
10
Q
Process of Transporting FA into mitochondria
A
- Fatty acyl CoA is first converted to acylcarnitine
- Acylcarnitine enters mitochondria (matrix side)
- acyl group is transferred back to CoA
11
Q
enzyme that converts Fatty acyl CoA to acylcarnitine
A
carnitine acyltransferase I
12
Q
carnitine acyltransferase I is bound to-
A
outer mitochondrial membrane
13
Q
Acylcarnitine enters the mitochondria via-
A
translocase
14
Q
enzyme that transfers acyl group back to CoA
A
carnitine acyltransferase II
15
Q
B-carbon atom (C3) is oxidized
A
B-oxidation pathway
16
Q
Number of atoms degraded in B-oxidation pathway at a time
A
2
17
Q
Reactions in B-oxidation pathway
A
Oxidation
Hydration
Oxidation
Cleavage
18
Q
Reaction in 1st Oxidation
A
Acyl CoA trans-Enoyl CoA
19
Q
enzyme in 1st oxidation
A
acyl CoA dehydrogenase
20
Q
coenzyme and oxidizing agent in 1st oxidation
A
FAD
21
Q
Reaction in Hydration
A
trans- Enoyl CoA ——-> L-3-Hydroxyacyl CoA
22
Q
enzyme in Hyration
A
enoyl CoA hydratase
23
Q
alcohol formed in Hydration
A
L-3-Hydroxyacyl CoA
24
Q
Reaction in 2nd Oxidation
A
L-3-Hydroxyacyl CoA ——-> 3-Ketoacyl CoA
25
enzyme in 2nd Oxidation
3-hydroxyacyl CoA dehydrogenase
26
coenzyme in 2nd Oxidation
NAD+
27
ketone formed in 2nd oxidation
3-Ketoacyl CoA
28
Reaction in Cleavage
3-Ketoacyl CoA --------> Acyl CoA + Acetyl CoA
29
Coenzyme and Cofactors in Cleavage
HS-CoA
30
Enzyme in Cleavage
B-ketothiolase
31
- shortened by two C atoms
| - undergoes another cycle of oxidation
Acyl CoA
32
will enter other cycles
Acetyl CoA
33
The formula for number of cycles
n/2 - 1
34
Each round generates one molecule each of:
FADH2
NADH
Acetyl CoA
Fatty Acyl CoA
35
Fate of NADH and FADH2 after B-oxidation
used in ETC
36
Fate of acetyl CoA after B-oxidation
enters TCA
37
Fate of acyl CoA after B-oxidation
undergoes the next cycle of oxidation
38
occurrence of Odd Chain fatty acids
bacteria
| microorganisms
39
Final Cleaving product of B-Oxidation of Odd Chain FA
propionyl CoA rather than acetyl CoA
40
3 enzymes that convert propionyl CoA to succinyl CoA
propionyl CoA carboxylase
methylmalonyl-CoA racemase
cobalamin (Vit B12)
41
Type of reaction in first step of conversion of Propionyl CoA to succinyl CoA
Carboxylation
| Hydrolysis of ATP
42
reaction in first step of conversion of Propionyl CoA to succinyl CoA
Propionyl CoA ----------> D-Methylmalonyl CoA
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Enzyme in first step
propionyl CoA carboxylase
44
Coenzyme in first step
| Cofactor in first step
biotin, ATP
| HCO3
45
Type of reaction in second step of conversion of Propionyl CoA to succinyl CoA
Racemization
46
reaction in second step of conversion of Propionyl CoA to succinyl CoA
D-Methylmalonyl CoA L-Methylmalonyl CoA
47
Enzyme in second step of conversion of Propionyl CoA to succinyl CoA
methylmalonyl-CoA racemase
48
Type of reaction in third step of conversion of Propionyl CoA to succinyl CoA
Izomerization
49
reaction in third step of conversion of Propionyl CoA to succinyl CoA
L-Methylmalonyl CoA Succinyl CoA
50
Enzyme in third step of conversion of Propionyl CoA to succinyl CoA
methylmalonyl CoA mutase
51
Coenzyme in third step of conversion of Propionyl CoA to succinyl CoA
Vitamin B12 (cobalamin)
52
makes reaction strong through intramolecular rearrangement
cobalamin
53
fate of Succinyl CoA
TCA
54
organelles containing enzyme catalase
Peroxisomes
55
catalyzes the dismutation of hydrogen peroxide into water and molecular oxygen
catalase
56
FA Synthesis occurs mainly in:
liver
adipocytes
mammary glands during lactation
57
location of FA Synthesis
cytoplasm
58
When glucose is plentiful-
large amounts of Acetyl CoA produced
| can be used for FA synthesis
59
3 Stages of FA synthesis
1. Transport of acetyl CoA into cytosol
2. Carboxylation of Acetyl CoA
3. Assembly of FA chain
60
destination of transport of acetyl CoA
cytosol
61
Through which acetyl CoA is exported from mitochondria
citrate transport system
62
Process of Transport of Acetyle CoA to the Cytosol
Acetyl CoA exported from mitochondrial via citrate transport system
Cytosolic NADH also converted to NADPH
63
number of ATP expended for each round of transport
2
64
number of NADPH generated for each molecule of acetyl CoA
1
65
will reduce oxaloacetate to malate
NADH
66
Process of Carboxylation of Acetyl CoA
carboxybiotin intermediate formed
ATP hydrolyzed
CO2 group in carboxybiotin transferred to acetyl CoA to form malonyl CoA
67
Reaction in Carboxylation of Acetyl CoA
HCO3 + ATP -----> ADP + Pi
Enz-Biotin ----> Enz-Biotin-COO-
Acetyl CoA ------> Malonyl CoA
68
5 Separate stages of Assembly of FA chain
1. Loading of precursors via thioester derivatives
2. Condensation of the precursors
3. Reduction
4. Dehydration
5. Reduction
69
A protein that is a component of the Fatty acyl synthase complex to which all intermediates of the FA synthesis are linked
almost identical to Acetyl CoA SH
Acyl Carrier Protein
| ACP-SH
70
common component of CoA and ACP
Pantothenic acid
71
amino acid end of ACP
Serine
72
prosthetic group of ACP
makes it possible for CoA to attach to ACP
phosphopantotheine
73
terminus of phosphopantotheine group of ACP where intermediates attach to
sulfhydryl terminus
74
active form of AcCoA
malonyl CoA
75
Reaction of Activation of AcCoA to malonyl CoA
Acetyl CoA + HCO3 + ATP ----> malonyl CoA + ADP + Pi + H
76
Enzyme used in activation of AcCoA
Acetyl CoA carboxylase
77
start of/ priming stage Elongation phase of FA Synthesis
formation of Acetyl ACP and Malonyl ACP
78
Reaction of Priming phase
AcCoA + HS-ACP Acetyl ACP + HS-COA
| Malonyl CoA + HS-ACP Malonyl ACP + HS-CoA
79
Reaction of Condensation phase
Acetyl ACP + Malonyl ACP ----> Acetoacetyl ACP + ACP + CO2
80
Reaction of Reduction phase
Acetoacetyl ACP + NADPH + H+ D-3- hydroxybutyryl ACP + NADP
81
Reaction of Dehydration phase
D-3-hydroxybutyryl ACP crotonyl ACP + H2O
82
Reaction of second reduction phase
Crotonyl ACP + NADPH + H ----> Butyryl ACP + NADP
83
Enzyme of priming phase
Acetyl transacylase
| Malonyl transacylase
84
Enzyme of Condensation phase
Acyl-malonyl ACP condensing enzyme
85
Enzyme of first reduction phase
B-ketoacyl ACP reductase
86
Enzyme of dehydration phase
3- Hydroxyacyl ACP dehydratase
87
Enzyme of second reduction phase
Enoyl ACP reductase
88
Product of Butyryl ACP and malonyl ACP in second round
C6-B-ketoacyl ACP
89
Product after Reduction, dehydration, second reduction of C6-B-ketoacyl ACP
C6-acyl ACP
90
hydrolyzes Palmitoyl ACP
thioesterase
91
Reaction of hydrolysis
Palmitoyl-ACP + H2O -----> Palmitate + HS-ACP
92
Overall reaction of palmitate synthesis from AcCoA and malonyl CoA
AcCoA + 7 Malonyl CoA + 14 NADPH + 14 H -----> Palmitate + 7 CO2 + 14 NADP + 8 HS-CoA + 6H2O
93
a dimer with antiparallel subunits
Fatty acid synthase
94
Number of domains in each subunits of Fatty acid synthase
3
95
Domain 1 enzymes
Acetyl Transacylase
Malonyl Transacylase
Ketoacyl-ACP synthase/ Acyl-Malonyl ACP condensing enzyme
96
Domain 2 enzymes
B-Ketoacyl ACP Reductase
3-Hydroxyacyl ACP Dehydratase
Enoyl ACP Reductase
ACP
97
Domain 3 enzyme
Thioesterase
98
common product of fatty acid synthesis
palmitate
99
location of synthesis of palmitate
ER
100
catalyze formation of double bonds to form unsaturated fatty acids
desaturases
101
plays an essential role in regulating FA synthesis and degradation
AcCoA
102
hormones that control carboxylase
glucagon
epinephrine
insulin
103
regulatory factors of carboxylase
citrate
palmitoyl CoA
AMP
104
is carried out by means of reversible phosphorylation
global regulation
105
is switched off by phosphorylation and activated by dephorsphorylation
AcCoA
106
stimulates FA synthesis causing dephosphorylation of carboxylase
Insulin
107
have the reverse effect: keep carboxylase in the inactive phophorylated state
Glucagon and Epinephrine
108
activates Protein Kinase
AMP
109
inhibits Proten kinase
ATP
110
is inactivated when energy charge is low
Carboxylase
111
allosterically stimulates AcCoA carboxylase
citrate
112
the level of citrate is high when
AcCoA and ATP are abundant
113
inhibits carboxylase
Palmitoyl carboxylase
114
Response to Fed state
Insulin increased
Inhibits hydrolysis of stored TAGs
Stimulations formation of malonyl CoA
FA remain in cytosol
115
inhibits carnitine acyltransferase I
malonyl CoA
116
Response to Starvation
Epinephrine and glucagon stimulate adipose cell lipase
Inactivate carboxylase
