Oxidation and biosynthesis of fatty acids Flashcards

1
Q

Stages of Fatty Acid Oxidation

A
  1. Activation of fatty acids
  2. Transport of Fatty Acyl CoA into the matrix of ` mitochondria
  3. Degradation to two-carbon fragments
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2
Q

Location of activation of fatty acids

A

outer mitochondrial membrane

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3
Q

Location of degradation to two carbon fragments

A

mitochondrial matrix

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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
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5
Q

enzyme that catalyzes conversion of FA to CoA thioesters

A

acyl-CoA synthetase

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6
Q

enzyme that hydrolyses PPi

A

pyrophosphatase

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7
Q

Reaction involved in Step 1 of FA Oxidation

A

FA + ATP Acyl adenylate + PPi

Acyl adenylate + HS—CoA Acyl CoA + AMP

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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

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9
Q

shuttling system used to transport FA into the mitochondria

A

carnitine shuttle system

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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
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11
Q

enzyme that converts Fatty acyl CoA to acylcarnitine

A

carnitine acyltransferase I

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12
Q

carnitine acyltransferase I is bound to-

A

outer mitochondrial membrane

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13
Q

Acylcarnitine enters the mitochondria via-

A

translocase

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14
Q

enzyme that transfers acyl group back to CoA

A

carnitine acyltransferase II

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15
Q

B-carbon atom (C3) is oxidized

A

B-oxidation pathway

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16
Q

Number of atoms degraded in B-oxidation pathway at a time

A

2

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17
Q

Reactions in B-oxidation pathway

A

Oxidation
Hydration
Oxidation
Cleavage

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18
Q

Reaction in 1st Oxidation

A

Acyl CoA trans-Enoyl CoA

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19
Q

enzyme in 1st oxidation

A

acyl CoA dehydrogenase

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20
Q

coenzyme and oxidizing agent in 1st oxidation

A

FAD

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21
Q

Reaction in Hydration

A

trans- Enoyl CoA ——-> L-3-Hydroxyacyl CoA

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22
Q

enzyme in Hyration

A

enoyl CoA hydratase

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23
Q

alcohol formed in Hydration

A

L-3-Hydroxyacyl CoA

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24
Q

Reaction in 2nd Oxidation

A

L-3-Hydroxyacyl CoA ——-> 3-Ketoacyl CoA

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25
Q

enzyme in 2nd Oxidation

A

3-hydroxyacyl CoA dehydrogenase

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26
Q

coenzyme in 2nd Oxidation

A

NAD+

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27
Q

ketone formed in 2nd oxidation

A

3-Ketoacyl CoA

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28
Q

Reaction in Cleavage

A

3-Ketoacyl CoA ——–> Acyl CoA + Acetyl CoA

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29
Q

Coenzyme and Cofactors in Cleavage

A

HS-CoA

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30
Q

Enzyme in Cleavage

A

B-ketothiolase

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31
Q
  • shortened by two C atoms

- undergoes another cycle of oxidation

A

Acyl CoA

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32
Q

will enter other cycles

A

Acetyl CoA

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33
Q

The formula for number of cycles

A

n/2 - 1

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34
Q

Each round generates one molecule each of:

A

FADH2
NADH
Acetyl CoA
Fatty Acyl CoA

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35
Q

Fate of NADH and FADH2 after B-oxidation

A

used in ETC

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36
Q

Fate of acetyl CoA after B-oxidation

A

enters TCA

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37
Q

Fate of acyl CoA after B-oxidation

A

undergoes the next cycle of oxidation

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38
Q

occurrence of Odd Chain fatty acids

A

bacteria

microorganisms

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39
Q

Final Cleaving product of B-Oxidation of Odd Chain FA

A

propionyl CoA rather than acetyl CoA

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40
Q

3 enzymes that convert propionyl CoA to succinyl CoA

A

propionyl CoA carboxylase
methylmalonyl-CoA racemase
cobalamin (Vit B12)

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41
Q

Type of reaction in first step of conversion of Propionyl CoA to succinyl CoA

A

Carboxylation

Hydrolysis of ATP

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42
Q

reaction in first step of conversion of Propionyl CoA to succinyl CoA

A

Propionyl CoA ———-> D-Methylmalonyl CoA

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43
Q

Enzyme in first step

A

propionyl CoA carboxylase

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44
Q

Coenzyme in first step

Cofactor in first step

A

biotin, ATP

HCO3

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45
Q

Type of reaction in second step of conversion of Propionyl CoA to succinyl CoA

A

Racemization

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46
Q

reaction in second step of conversion of Propionyl CoA to succinyl CoA

A

D-Methylmalonyl CoA L-Methylmalonyl CoA

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47
Q

Enzyme in second step of conversion of Propionyl CoA to succinyl CoA

A

methylmalonyl-CoA racemase

48
Q

Type of reaction in third step of conversion of Propionyl CoA to succinyl CoA

A

Izomerization

49
Q

reaction in third step of conversion of Propionyl CoA to succinyl CoA

A

L-Methylmalonyl CoA Succinyl CoA

50
Q

Enzyme in third step of conversion of Propionyl CoA to succinyl CoA

A

methylmalonyl CoA mutase

51
Q

Coenzyme in third step of conversion of Propionyl CoA to succinyl CoA

A

Vitamin B12 (cobalamin)

52
Q

makes reaction strong through intramolecular rearrangement

A

cobalamin

53
Q

fate of Succinyl CoA

A

TCA

54
Q

organelles containing enzyme catalase

A

Peroxisomes

55
Q

catalyzes the dismutation of hydrogen peroxide into water and molecular oxygen

A

catalase

56
Q

FA Synthesis occurs mainly in:

A

liver
adipocytes
mammary glands during lactation

57
Q

location of FA Synthesis

A

cytoplasm

58
Q

When glucose is plentiful-

A

large amounts of Acetyl CoA produced

can be used for FA synthesis

59
Q

3 Stages of FA synthesis

A
  1. Transport of acetyl CoA into cytosol
  2. Carboxylation of Acetyl CoA
  3. Assembly of FA chain
60
Q

destination of transport of acetyl CoA

A

cytosol

61
Q

Through which acetyl CoA is exported from mitochondria

A

citrate transport system

62
Q

Process of Transport of Acetyle CoA to the Cytosol

A

Acetyl CoA exported from mitochondrial via citrate transport system

Cytosolic NADH also converted to NADPH

63
Q

number of ATP expended for each round of transport

A

2

64
Q

number of NADPH generated for each molecule of acetyl CoA

A

1

65
Q

will reduce oxaloacetate to malate

A

NADH

66
Q

Process of Carboxylation of Acetyl CoA

A

carboxybiotin intermediate formed
ATP hydrolyzed
CO2 group in carboxybiotin transferred to acetyl CoA to form malonyl CoA

67
Q

Reaction in Carboxylation of Acetyl CoA

A

HCO3 + ATP —–> ADP + Pi
Enz-Biotin —-> Enz-Biotin-COO-
Acetyl CoA ——> Malonyl CoA

68
Q

5 Separate stages of Assembly of FA chain

A
  1. Loading of precursors via thioester derivatives
  2. Condensation of the precursors
  3. Reduction
  4. Dehydration
  5. Reduction
69
Q

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

A

Acyl Carrier Protein

ACP-SH

70
Q

common component of CoA and ACP

A

Pantothenic acid

71
Q

amino acid end of ACP

A

Serine

72
Q

prosthetic group of ACP

makes it possible for CoA to attach to ACP

A

phosphopantotheine

73
Q

terminus of phosphopantotheine group of ACP where intermediates attach to

A

sulfhydryl terminus

74
Q

active form of AcCoA

A

malonyl CoA

75
Q

Reaction of Activation of AcCoA to malonyl CoA

A

Acetyl CoA + HCO3 + ATP —-> malonyl CoA + ADP + Pi + H

76
Q

Enzyme used in activation of AcCoA

A

Acetyl CoA carboxylase

77
Q

start of/ priming stage Elongation phase of FA Synthesis

A

formation of Acetyl ACP and Malonyl ACP

78
Q

Reaction of Priming phase

A

AcCoA + HS-ACP Acetyl ACP + HS-COA

Malonyl CoA + HS-ACP Malonyl ACP + HS-CoA

79
Q

Reaction of Condensation phase

A

Acetyl ACP + Malonyl ACP —-> Acetoacetyl ACP + ACP + CO2

80
Q

Reaction of Reduction phase

A

Acetoacetyl ACP + NADPH + H+ D-3- hydroxybutyryl ACP + NADP

81
Q

Reaction of Dehydration phase

A

D-3-hydroxybutyryl ACP crotonyl ACP + H2O

82
Q

Reaction of second reduction phase

A

Crotonyl ACP + NADPH + H —-> Butyryl ACP + NADP

83
Q

Enzyme of priming phase

A

Acetyl transacylase

Malonyl transacylase

84
Q

Enzyme of Condensation phase

A

Acyl-malonyl ACP condensing enzyme

85
Q

Enzyme of first reduction phase

A

B-ketoacyl ACP reductase

86
Q

Enzyme of dehydration phase

A

3- Hydroxyacyl ACP dehydratase

87
Q

Enzyme of second reduction phase

A

Enoyl ACP reductase

88
Q

Product of Butyryl ACP and malonyl ACP in second round

A

C6-B-ketoacyl ACP

89
Q

Product after Reduction, dehydration, second reduction of C6-B-ketoacyl ACP

A

C6-acyl ACP

90
Q

hydrolyzes Palmitoyl ACP

A

thioesterase

91
Q

Reaction of hydrolysis

A

Palmitoyl-ACP + H2O —–> Palmitate + HS-ACP

92
Q

Overall reaction of palmitate synthesis from AcCoA and malonyl CoA

A

AcCoA + 7 Malonyl CoA + 14 NADPH + 14 H —–> Palmitate + 7 CO2 + 14 NADP + 8 HS-CoA + 6H2O

93
Q

a dimer with antiparallel subunits

A

Fatty acid synthase

94
Q

Number of domains in each subunits of Fatty acid synthase

A

3

95
Q

Domain 1 enzymes

A

Acetyl Transacylase
Malonyl Transacylase
Ketoacyl-ACP synthase/ Acyl-Malonyl ACP condensing enzyme

96
Q

Domain 2 enzymes

A

B-Ketoacyl ACP Reductase
3-Hydroxyacyl ACP Dehydratase
Enoyl ACP Reductase
ACP

97
Q

Domain 3 enzyme

A

Thioesterase

98
Q

common product of fatty acid synthesis

A

palmitate

99
Q

location of synthesis of palmitate

A

ER

100
Q

catalyze formation of double bonds to form unsaturated fatty acids

A

desaturases

101
Q

plays an essential role in regulating FA synthesis and degradation

A

AcCoA

102
Q

hormones that control carboxylase

A

glucagon
epinephrine
insulin

103
Q

regulatory factors of carboxylase

A

citrate
palmitoyl CoA
AMP

104
Q

is carried out by means of reversible phosphorylation

A

global regulation

105
Q

is switched off by phosphorylation and activated by dephorsphorylation

A

AcCoA

106
Q

stimulates FA synthesis causing dephosphorylation of carboxylase

A

Insulin

107
Q

have the reverse effect: keep carboxylase in the inactive phophorylated state

A

Glucagon and Epinephrine

108
Q

activates Protein Kinase

A

AMP

109
Q

inhibits Proten kinase

A

ATP

110
Q

is inactivated when energy charge is low

A

Carboxylase

111
Q

allosterically stimulates AcCoA carboxylase

A

citrate

112
Q

the level of citrate is high when

A

AcCoA and ATP are abundant

113
Q

inhibits carboxylase

A

Palmitoyl carboxylase

114
Q

Response to Fed state

A

Insulin increased
Inhibits hydrolysis of stored TAGs
Stimulations formation of malonyl CoA
FA remain in cytosol

115
Q

inhibits carnitine acyltransferase I

A

malonyl CoA

116
Q

Response to Starvation

A

Epinephrine and glucagon stimulate adipose cell lipase

Inactivate carboxylase