Amino Acid Metabolism

Front 1

sources of amino acids for amino acid pool (3)

Back 1

dietary protein, degraded body protein, synthesis

Front 2

fates of amino acids from pool (3)

Back 2

body protein, synthesis of other nitrogen compounds, metabolism for energy

Front 3

Positive nitrogen balance, def and most common populations

Back 3

more nitrogen in than out; growing children, pregnancy, convalescence

Front 4

negative nitrogen balance, def and most commonly affected populations

Back 4

more nitrogen out than in; trauma and injury, diet deficient in essential aa's

Front 5

What do you call α-ketoglutarate when a nitrogen group is added to it?

Back 5

α-keto acid

Front 6

form of nitrogen excreted by 1 fish, 2 people, 3 birds

Back 6

1 ammonia (toxic), 2 urea, 3 uric acid (minimize water loss)

Front 7

which amino acids have no associated transaminase? (3) What must happen to them instead?

Back 7

arg, lys, phe. Must be converted to another aa, then transaminated.

Front 8

What is arginine converted to prior to being transaminated?

Back 8

ornithine

Front 9

What is phenylalanine converted to prior to being transaminated?

Back 9

tyrosine

Front 10

ala, cys, glyc, ser, thr, trp: end metabolite?

Back 10

pyruvate

Front 11

required cofactor for all aminotransferase reactions?

Back 11

pyridoxal phosphate (vit B6)

Front 12

symptoms of vit B6 deficiency

Back 12

neurologic symptoms: irritability, confusion, nervousness, extremeties, convulsive seizures

Front 13

Clinical problem with oxaloacetate deficiency?

Back 13

CAC cannot turn, also results from α-ketoglutarate, pyruvate deficiencies.

Front 14

Molecules that overlap between urea cycle and CAC? (3) Result of excesses/deficiencies in these?

Back 14

oxaloacetate, α-ketoglutarate, pyruvate. DEFICIENCIES: prevent CAC from proceeding as normal, which means no ATP synthesis/ox-phosph. EXCESSES: gluconeogenesis.

Front 15

fuels for urea cycle?

Back 15

ammonia, aspartate

Front 16

ATP requirements of urea cycle

Back 16

costs 3 ATP, but makes 2 ATP from fumarate in CAC/ox-phos

Front 17

middle part of krebs bi-cycle

Back 17

fumarate => malate => oxaloacetate (+ L-glutamate) => aspartate (+ α-ketoglutarate) => argininosuccinate => fumarate

Front 18

irreversible enzymes of the urea cycle?

Back 18

N-acetyl glutamate, carbamyl phosphate synthease, arginase

Front 19

Describe the fate of citrulline in 1 hepatocytes, 2 kidney proximal tubule cells, and 3 NO-producing cells

Back 19

LIVER: citrulline => arg => urea. KIDNEY: citrulline => arg. NO-Cells: citrulline => NO

Front 20

Generic aminotransferrase reaction?

Back 20

amino acid + α-ketoglutarate <=> α-keto acid + glutamate

Front 21

Aspartate aminotransferrase reaction?

Back 21

alanine + α-ketoglutarate <=[ALT]=> pyruvate + glutamate

Front 22

Alanine aminotransferrase reaction?

Back 22

aspartate + α-ketoglutarate <=[AST]=> oxaloacetate + glutamate

Front 23

Demination of glutamate, rxn? Why is this reaction unusual?

Back 23

glutamate + NAD(P)+ + H2O <=> α-ketoglutarate + NH4+ + NAD(P)H. Unusual because this enzyme can use NAD+ or NADP+ as a cofactor.

Front 24

in the kidneys, phenylalanine is coverted to ______ and glycine to _______

Back 24

tyrosine, serine

Front 25

fate of glutamine in the kidneys

Back 25

metabolized to ammonia in order to maintain pH by proton excretion

Front 26

enzyme responsible for detoxing ammonia?

Back 26

glutamine synthetase

Front 27

trace the fate of NH4+ in the peripheral tisssues

Back 27

NH4+ incorporated into glutamine (via glutamine synthetase) => glutamine shuttles NH4+ to liver => liver incorporates NH4+ into urea => urea is excreted by kidneys

Front 28

describe the steps of the glucose-alanine cycle (4)

Back 28

1 alanine travels to liver via circulation, 2 alanine transdeaminated (by ALT) => pyruvate, 3 pyruvate is used in gluconeogenesis, 4 glucose travels back to muscle

Front 29

purpose of glucose-alanine cycle?

Back 29

provide glucose for skeletal muscle

Front 30

urea cycle enzymes with deficienies (4), inheritance patterns

Back 30

AUTOSOMAL: carbamyl phosphate synthetase, argininosuccinic acid synthetase, argininosuccinase, arginase. X-LINKED: ornithine transcarbamylase

Front 31

symptoms of urea cycle enzyme deficiency

Back 31

inc [glutamine] => brain swelling, swollen astrocytes; inc [ammonia] => hypothermia, apnea; additional symptoms include lethargy and behavioral abnormalities

Front 32

Usual time frame for deficiencies of urea cycle enzymes to appear

Back 32

24-48 hr after birth when mom's metabolism is no longer compensating

Front 33

arginase deficiency, symptoms. Relative ammonia levels?

Back 33

progressive spastic quadriplegia, mental retardation. Ammonia levels are relatively low compared to other urea cycle enzyme deficiencies.

Front 34

essential aa's? (10)

Back 34

NONPOLAR: valine, leucine, methionine, isoleucine. AROMATIC: phenylalanine, tryptophan. POLAR: threonine. BASIC: lysine, arginine, histidine. (ornithine can be synthesized, but is used for purposes other than protein synthesis)

Front 35

nonessential aa's (10)

Back 35

NONPOLAR: glycine, alanine. AROMATIC: tyrosine. POLAR: serine, cysteine, proline, asparagine, glutamine. ACIDIC: aspartate, glutamate.

Front 36

ketogenic aa's (8)

Back 36

AcCoA: leucine, isoleucine, threonine. Acetoacetate: leucine, lysine+, phenylalanine, tyrosine, tryptophan

Front 37

gluconeogenic aa's (18)

Back 37

all amino acids besides lysine and leucine

Front 38

gluconeogenic aa's that are precursors to pyruvate (6). Next step

Back 38

glycine, alanine, serine, threonine, cysteine, tryptophan

Front 39

gluconeogenic aa's that are precursors to α-ketoglutarate (5)

Back 39

proline, glutamine, arginine, histidine, glutamate

Front 40

gluconeogenic aa's that are precursors to Succinyl-CoA (3)

Back 40

valine, methionine, isoleucine

Front 41

gluconeogenic aa's that are precursors to fumarate (3)

Back 41

phenylalanine, tyrosine, aspartate

Front 42

gluconeogenic aa's that are precursors to oxaloacetate (2)

Back 42

asparagine, aspartate