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Biochem > Amino acid metabolism > Flashcards

Amino acid metabolism Flashcards

1
Q

Compounds that increase ubiquitin and UPS synthesis; function by increasing amino acid release

A

Glucocorticoids

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2
Q

Amino acid release/breakdown occurs in the fed or fasted state?

A

Fasted/stressed states

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3
Q

Function of the ubiquitin-proteasome system

A

Degrades cytosolic and nuclear proteins

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4
Q

Glucocorticoids increase this

A

Ubiquitin and UPS synthesis
(thereby increasing amino acid release)

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5
Q

Glucocorticoids promote breakdown of TGs to this

A

Glycerol

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6
Q

Glucocorticoids have this effect on glycogen storage

A

Promote glycogen synthesis

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7
Q

Elevated levels of this indicate increased protein catabolism in muscle cells

A

BUN

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8
Q

This lab result can indicate the effect of glucocorticoids

A

Elevated BUN

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9
Q

Most of the nitrogen excreted in the urine is in the form of this

A

Urea

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10
Q

NH4+ excretion increases during this

A

Acidosis

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11
Q

N balance when intake is greater than losses

A

Positive

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12
Q

N balance when intake = losses

A

Balanced
Adult needs 0.8 g/kg/day

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13
Q

N balance where intake is less than losses

A

Negative

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14
Q

Protein-energy malnutrition (PEM) that is protein but not calorie deficient
Edema present due to deficient serum albumin

A

Kashiorkor

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15
Q

Protein-energy malnutrition (PEM) that involves calorie and protein deficient
Wasting

A

Marasmus

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16
Q

Only 2 amino acids not degraded/used for gluconeogenesis

A

Leucine and Lysine

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17
Q

10 essential amino acids

A

Phe, Val, The, Trp, Ile, Met, *His, *Arg, Leu, Lys

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18
Q

Tyrosine and cysteine are examples of this type of amino acid

A

Conditional amino acids

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19
Q

Enzyme that catalyzes:
Alpha-ketoglutarate + NH3 + NAD(P)H → Glutamate + NAD(P)+

A

Glutamate dehydrogenase

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20
Q

Enzyme that incorporates NH3 into alpha-ketoglutarate

A

Glutamate dehydrogenase

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21
Q

Enzymes that move NH3 from glutamate to various other carbon structures

A

Aminotransferases/transaminases

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22
Q

Elevated levels of this indicate liver damage/problem

A

ALT

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23
Q

Molecule that does non-toxic transport of amino groups

A

Glutamine

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24
Q

Enzyme that catalyzes:
Pyruvate + glutamate ↔ Alanine + alpha-ketoglutarate

A

ALT

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25
Q

Enzyme that catalyzes:
Oxaloacetate + glutamate ↔ Aspartate + alpha-ketoglutarate

A

AST

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26
Q

Pancreatic zymogens are secreted into the small intestine via this

A

Pancreatic duct

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27
Q

Tyrpsinogen is activated by this

A

Enteropeptidase

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28
Q

Enteropeptidase is secreted by these cells

A

Intestinal mucosal cells

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29
Q

Amino acid transport primarily occurs by this mechanism

A

Na+ dependent secondary active transport

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30
Q

Condition caused by defective transport system for large neutral amino acids like Trp

A

Hartnup disease

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31
Q

Hartnup disease can lead to a deficiency of this

A

Niacin

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32
Q

Niacin is made from this

A

Trp

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33
Q

Defective transport of Lys, Arg, Ornithine, and Cystine

A

Cystinuria

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34
Q

Cystinuria is due to defective transport of these

A

Lys, Arg, Ornithine, and Cystine

35
Q

Lysosomes are acidified by this structure that pumps H+ in

A

Vacuolar H+ ATPase

36
Q

Lysosomal proteins with optimal activity of pH 5

A

Cathepsins

37
Q

Urea is increased in fasted or fed state?

A

BOTH
Fed = excess nitrogen = converted to urea
Fasted = protein hydrolysis

38
Q

Type of amino acids that are used as fuel for muscle

A

Branched chain amino acids (Leu, Ile, and Val)

39
Q

Amino groups of branched chain amino acids are transferred to these two molecule to form alanine or glutamine

A

Pyruvate and alpha-ketoglutarate

40
Q

Amino groups of branched chain amino acids are transferred to pyruvate and alpha-ketoglutarate to form these two molecules

A

Alanine or glutamine

41
Q

Urea excretion is highest during this point in fasting

A

First few days
(drops after brain adapts to ketone bodies)

42
Q

Required coenzyme for all aminotransferases

A

PLP: pyridoxal phosphate

43
Q

PLP is synthesized from this vitamin

A

B6

44
Q

Breakdown of glutamine by glutaminase produces these 2 products

A

Glutamate and NH4

45
Q

Aminotransferases make it possible to shift most amino groups to this

A

Alpha-ketoglutarate, forming glutamate

46
Q

Enzyme that catalyzes:
Glutamine + H2O → Glutamate + NH4+

A

Glutaminase

47
Q

Breakdown of glutamine is significant in the kidney during this

A

Acidosis
Excretes H+ as NH4+

48
Q

4 main enzymes releasing free NH4+

A

Aminotransferases for almost all aa’s
Glutaminase
Serine and threonine dehydratases
Purine nucleotide pathway

49
Q

3 enzymes that convert NH4+ to organic form

A

Glutamate dehydrogenase (GDH)
Glutamine synthetase
Carbamoyl phosphate synthetase I (CPS I)

50
Q

Enzyme that catalyzes:
ATP + NH4+ + Glutamate → Glutamine + ADP + Pi

A

Glutamine synthetase

51
Q

Major nitrogenous excretory product
Nontoxic carrier of nitrogen atoms
Made in liver from NH4+, HCO3- and amino group of aspartate

A

Urea

52
Q

First step in urea cycle

A

Carbamoyl phosphate synthetase I (CPSI)

53
Q

Enzyme that catalyzes:
NH4+ + CO2 + 2ATP → Carbamoyl phosphate + 2ADP + Pi

A

Carbamoyl phosphate synthetase I (CPSI)

54
Q

CPS I is in this cellular location

A

Mitochondria

55
Q

Molecule that supplies the first nitrogen in the urea cycle

A

NH4+

56
Q

Enzyme that catalyzes:
Carbamoyl-phosphate + Ornithine → Citrulline

A

Ornithine transcarbamylase (OTCase)

57
Q

Intermediate that is transported out of the mitochondria in the urea cycle

A

Citrulline

58
Q

Enzyme that catalyzes:
Citrulline + aspartate → Argininosuccinate

A

Arginino-succinate synthase

59
Q

Molecule that supplies the second nitrogen in the urea cycle

A

Aspartate

60
Q

Enzyme that catalyzes:
Argininosuccinate → Fumarate + Arginine

A

Arginino-succinate lyase

61
Q

The “second cycle” of the urea cycle refers to this

A

Fumarate can be recycled back to aspartate by conversion to oxaloacetate, then transamination

62
Q

Enzyme that catalyzes:
Arginine → Urea + Ornithine

A

Arginase

63
Q

Does fed or fasted state induce urea cycle enzyme synthesis?

A

Fasting

64
Q

Diet that induces urea cycle enzyme synthesis

A

High protein diet

65
Q

N-acetyl-glutamate synthesis is allosterically stimulated by this

A

Arginine

66
Q

Arginine allosterically stimulates the synthesis of this

A

N-acetyl-glutamate

67
Q

N-acetyl-glutamate activates this enzyme

A

CPS I

68
Q

CPS I is activated by this

A

N-acetyl-glutamate

69
Q

More active CPS I causes more or less free ammonia?

A

Less

70
Q

Does acidosis slow or speed up the urea cycle?

A

Slows
glutaminase releases NH4+ to dispose of excess protons

71
Q

Amino acid that can be used to synthesize nitric oxide for signaling via nitric oxide synthase

A

Arginine

72
Q

Enzyme that catalyzes:
Arginine + NADPH + O2 → NO + NADP+ + citrulline

A

Nitric oxide synthase

73
Q

BUN is low in this condition

A

Liver failure

74
Q

BUN is associated with this in liver failure

A

High ammonia

75
Q

If NH4+ is high, these two amino acids are generally high in the blood

A

Glutamine and glycine

76
Q

Result of acquired hyperammonemia where liver disease compromises its ability to metabolize toxins and xenobiotics (CYP system)
Can affect the brain, leading to coma and death

A

Hepatic encephalopathy

77
Q

Normally the main source of blood urea

A

Gut bacteria

78
Q

Gut bacteria produce NH4+ from these 2 compounds

A

Dietary nitrogen compounds
Rehydrolyze urea

79
Q

Congenital hyperammonemia that is autosomal recessive, most common, and sees NO increase in urinary orotic acid

A

Carbamoyl phosphate synthetase I deficiency

80
Q

Congenital hyperammonemia that is X-linked and results in excessive orotic acid in the urine

A

Ornithine transcarbamoylase deficiency

81
Q

Ornithine transcarbamoylase deficiency results in excess amounts of this in the urine

A

Orotic acid

82
Q

3 Alternate pathways that help dispose of excess nitrogen and help in mild cases of hyperammonemia

A

Phenyl butyrate
Phenyl acetate
Benzoic acid

83
Q

This is activated to a CoA derivative and glutamine is attached, and the produce excreted to help dispose of excess nitrogen

A

Phenyl acetate

84
Q

This is activated to benzoyl CoA, then a glycine is attached and the complex excreted to help dispose of excess nitrogen

A

Benzoic acid

Biochem (21 decks)

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