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Nutrition And Metabolism > Protein And Amino Acid Metabolism > Flashcards

Protein And Amino Acid Metabolism Flashcards

1
Q

What happens to excess amino acids in the body

A

Cannot be stored so used for fuel

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2
Q

Kwashiorkor

A

Protein deficiency but adequate calories

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3
Q

Famine edema

A

Inadequate synthesis of plasma proteins like albumin so fluid Escape into tissues (oncotic pressure)

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4
Q

Marasmus

A

Protein calorie deficiency

Starvation

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5
Q

People at risk of protein malnutrition

A

Pregnant and lactating women

individuals with eating disorders

chronic alcoholics

substance abusers

hospital patients with major protein
needs

elderly

clinical chronically ill

individuals patience with genetic disorders in amino acid metabolism

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6
Q

Essential amino acids (PVT TIM HALL)

A

Phenylalanine
Valine
Tryptophan

Threonine
Isoleucine
Methionine

Histidine
Arginine
Leucine
Lysine

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7
Q

Is arginine always an essential amino acids

A

No

essential in children because of active growth but nonessential in adults

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8
Q

What is a glucogenic Amino acid

A

Product can enter gluconeogenesis

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9
Q

What is a ketogenic amino acid

A

Product intermediate of lipids metabolism or Ketone bodies

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10
Q

Positive nitrogen balance

A

More intake than excretion

Growth, pregnancy, tissue repair

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11
Q

Negative N balance

A

N excretion > intake

Starvation
Malnutrition
Illness
Surgery

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12
Q

General rédaction of amino acids

A

Transamination

Oxidative deamination

Decarboxylation

Transdeamination

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13
Q

Transamination

A

Caralyzed by transaminases (aminotransferase)

Transfer of NH2 to produce another AA

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14
Q

Co factor of transaminases

A

Pyridoxal phosphate from vit B6

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15
Q

Main compound in AA metabolism

A

Glutamate
Glutamine
a-KG

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16
Q

Neutral transport and storage form of ammonia

A

Glutamine

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17
Q

Glutamate dehydrogenase rxn

A

a-KG ——-> glutamate by glutamate dehydrogenase

Glutamate ——> glutamine by glutamine synthétase

Glutamine —-> glutamate by glutaminase

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18
Q

Genetic disorder in which glutamate dehydrogenase always activated due to binding site of GTP mutation

A

Hyperinsulinism - hyperammonemia syndrome with hypoglycemia

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19
Q

Where in the body do you find amino acids oxidase

A

The kidney

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20
Q

Decarboxylation of AA

A

Removal of CO2 by glu decarboxylase to form GABA

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21
Q

Transdeamination

A

Coupling of aminotransferase

with glutamate dehydrogenase reaction ( transamination+ deamination )

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22
Q

Tryptophan metabolized to

A 
97%: 
Alanine 
Acetyl Coa
CO2 
Formate

3% :
Melatonin
Serotonin
Nicotinate ( niacin )

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23
Q

Serotonin function

A 
Neurotransmission 
Behavioral processes (!appetite, agression , sleep ,sensory perceptions, depression 
Vasoconstriction
Regulate circadian cycle , intestinal peristalsis
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24
Q

Agonist of serotonin

A

LSD

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25
Q

Antidepressants and their MOA

A

Paxil
Prozac
Zoloft
Inhibits serotonin reuptake

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26
Q

Hartnup disease

A

Defect in transportation or absorption of amino acids in intestine
Leads to essential amino acid deficiency and nicotinamide deficiencies

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27
Q

Hartnup disease symptoms

A

Hereditary pellagra like skin rash

Temporary cerebellum ataxia

Renal amino aciduria

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28
Q

Hartnup disease 3 D’s

A

Dermatitis
Diarrhea
Dementia

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29
Q

What factors precipitate hartnup disease

A 
Sunburn
Fever
Inadequate nutrition 
Irregular diet 
Stress
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30
Q

Under what form is NH3 excreted

A

Urea

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31
Q

Direct sources of ammonia in liver

A

Glutamate
Glutamine (extrahepwtic tissues )
Alanine (muscles )

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32
Q

Organs that contributes the most to waste nitrogen

A

Muscles

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33
Q

Allostérie activator of CPSI

A

N acetylglutamate

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34
Q

Difference between CPSI and CPSII

A

CPSI only in mitochondria and uses NH3 in urea cycle

CPSII only in cytosol and uses glutamine in pyrimidine synthesis

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35
Q

Organ where urea cycle takes place

A

Liver

36
Q

Reactions of urea cycle in mitochondria

A

Ammonia —-> carbamoyl phosphate
By CPSI

Carbamoyl phosphate —-> citrulline
By ornithine transcarbamoylase and addition of ornithine

37
Q

Urea cycle rxn in cytosol

A

Citrulline —-> argininosuccinage
By argininosuccinate synthase and addition of aspartic acid

Argininosuccinate —-> arginine
By argininosuccinase and removal of fumarate

Arginine ——> ornithine
By arginase and removal of urea

38
Q

Fate of fumarate in urea cycle

A

Glucose source
Aspartate source
Energy source

39
Q

2 hypothesis of urea malfunctions leading to coma

A

Depletion of a-KG because too much NH4 allow conversion of a-KG to glutamate by glutamate dehydrogenase. So less a-KG free for TCA cycle -> less oxidative phosphorylation which is important for neurons

Toxicity of glutamine due to its accumulation in astrocytes. Leads to osmotic pressure -> swelling -> edema

40
Q

Clinical manifestations of urea cycle malfunctions

A 
Vomiting 
Seizures
Somnolence 
Coma
Death
41
Q

Most common urea cycle enzyme malfunction

A

Ornithine gras carbamoylase

42
Q

Symptoms of hyperammonemia type 2 (ornithine transcarbamoylase deficiency)

A

Mild : episodic hyperammonemia when high protein intake or infection

Severe : neonatal hyperammonemic coma, death , mental retardation, cerebral palsy when survive

High glutamine level

43
Q

Hyperammonemia type 1 due to

A

CPSI deficiency

44
Q

Citrullenemia

A

Hyperammonemia + high citrulline level

Due to argininosuccinate synthase deficiency

45
Q

Management of citrullinemia

A

Arginine feeding (enhance citrulline excretion )

Benzoate feeding (divert ammonia to hyppurate)

46
Q

Emergency Management of hyperammonemia

A

IV glucose and lipid (stop protein catabolism )

Hemodialysis

Phenylacetate for gln conjugation-> enhance n acetylglutamate synthase

47
Q

Long term Management of hyperammonemia

A 
Less dietary protein intake 
Adequate essential AA 
Non protein calories 
Arginine or citrulline if necessary 
Drugs (phenylbutyrate , benzoate)
48
Q

Phenylalanine main product

A

Tyrosine

49
Q

Tyrosine metabolism end product

A

Fumarate + acetoacetate

50
Q

Phenylalanine metabolism overview

A

Phe ——> tyrosine
By phe hydroxylase + H4biopterin

Tyr——> p hydroxylphenyl pyruvate
By aminotransferase

hydroxylphenyl pyruvate —-> homogentisate
By oxidase

Homogentisate —-> maleyl acetoacetate
By oxidase

Maleyl acetoacetate ——> fumaryl acetoacetate
By isomerase

Fumaryl acetoacetate——> acetoacetate + fumarate
By hydrolase

51
Q

Tyrosinemias

A

Deficiency in tyr aminotransferase

Accumulation of tyr and metabolites

52
Q

Type II Tyrosinemias (oculocutaneous)

A

Eye & skin lesions
Mental retardation
Cornea keratitis
Palm hyperkeratosis +ulcers

53
Q

Type I tyrosenemias (hepatorenal )

A

Liver failure
Renal tubular dysfunction
Rickets
Polyneuropathy

Caused by fumarylacetoacetate hydrolase deficiency

54
Q

Type I tyrosinemia management

A

Diet
Nitisone
Liver transplant

55
Q

Alcaptonuria

A

homogentisate oxidase deficiency so accumulation of homogentisate in urine

Urine looks intense dark color

Deposition of dark pigment in cartilage and connective tissue

56
Q

Albinism

A

Deficiency of tyrosinase
So no skin or hair color
Sun sensitivity
Photophobia

57
Q

Phenylketonuria

A 
Phenylalanine hydroxylase deficiency (classical) 
Or 
H4biopterin deficiency (non classical)
58
Q

Phenylketonuria symptoms

A

Mental retardation
Seizures
Microcéphaly

59
Q

PKU type I management

A

Low diet in phe
Adequate diet with tyrosine
Screening of neonate so that therapy can work
Long term maintenance of diet

60
Q

Tyrosine precursors of

A

Catecholamines ( l dopa, dopamine , norepinephrine , epinephrine

61
Q

Treatment of Parkinson’s disease

A

Dopa because can cross blood brain barrier ( dopamine can’t )

62
Q

If high level of homovanillate , what does it mean

A

Dopamine metabolism malfunction

63
Q

If high level of vanillykmandelate, what does it mean

A

Epinephrine and norepinephrine metabolism malfunction

64
Q

Branched chain AA

A

Leucine
Isoleucine
Valine

65
Q

Leucine catabolism

A

Leucine ——> isovaleryl coa ——> acetoacetyl coa

66
Q

Valine and isoleucine catabolism

A

Aa —-> some buturyl stuff ——-€ propionyl COA —biotin—-> methylmalonyl coa ——> succinyl coa

67
Q

Disorders of BCAA

A

Propionicacidemia

Maple syrup disease

Isovaleric acidemia

Methylmalonicacidemi

68
Q

Propionic acidemia

A

Deficient carboxylase or biotin preventing formation of methylmalonyl coa

So propionyl coa accumulation

69
Q

Propionicacidemia symptoms

A

Hypoglycemia
Hyperammonemia
Less succinyl coa

70
Q

Maple syrup urine disease

A

Val île leu metabolism blocked because ketoacid dehydrogenase deficient

So hypoglycemia and ketoacidosis

Mental retardation

71
Q

Isovaleric acidemia

A

Isovaleryl coa dehydrogenase deficiency

Isovaleryl coa accumulation So form toxic metabolites in kidney (isovaleryl glycine, isovalerylcarnitine )

72
Q

Isovaleric acidemia symptoms

A

Coma
Acidosis
Ketonuria
Sweaty feet odour

73
Q

Isovaleric acidemia management

A

Diet management
Newborn screening
Crisis management

74
Q

Methylmalonic acidemia

A

Defective methylmalonyl mutass or cobalamin

So methylmalonyl coa accumulation which inhibits pyruvate carboxylase

75
Q

Methylmalonyl acidemia symptoms

A 
Hyperammonemia 
Coma 
Nephropathy
CNS involvement 
Hypoglycemia 
Ketoqcidosis
76
Q

Cysteine synthesis pathway

A

Homocysteine + serine ——> cystathione
By cysthationine synthase

cystathionine——> a-ketobutyrate and cysteine
By cystathionase

77
Q

Cofactor needed for cysteine synthesis

A

PLP (pyridoxal phosphate )

78
Q

Homocysteine synthesis pathway

A

Methionine ——> s Adenosylmethionine

s Adenosylmethionine —-> a adenosylhomocysteine

S adenosylhomocysteine—-> homocysteine

79
Q

How to get from homocysteine to methionine

A

Add vit b12 + folic acid

80
Q

Hypercysteinemja

A

Deficiency of cystathionine synthase
Accumulation of homocysteine
And remethylation causes high methionine levels

81
Q

Hyperhomocysteinemoa symptoms

A

Mental retardation
Dislocated lenses after age 3
Osteoporosis

82
Q

Management of hyperhoomocysteinemia

A

Restrictions of methionine intake
Feeding of beta une and pyridoxine
Feeding of folate

83
Q

What disease is high level homocysteine associated with

A

Mortality in coronary heart disease
Dementia
Alzeihmer disease

84
Q

Methyl donor to homocysteine to obtain methionine

A

N5-methyltetrahydrofolate

85
Q

Serine precursor

A

Glucose

86
Q

Glycine precursors

A

Serine or threonine

Nutrition And Metabolism (17 decks)

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