Protein 3

Question 1

What are Transamination and deamination methods for?

Answer 1

Protein degradation

Question 2

Products of Transamination

Answer 2

Forms a new AA and a new α-keto acid

Question 3

2 Primary Enzymes:

transaminases

Answer 3

–Alanine aminotransferase (ALT)

–Aspartate aminotransferase (AST)

Question 4

Alanine + alpha keto acid =

Answer 4

Pyruvate + alpha AA

Question 5

Alpha keto acid + aspartate =

Answer 5

Alpha AA + oxaloacetate

Question 6

Carbon skeleton of glutamate

Answer 6

Alpha keto acid

Question 7

Carbon skeleton of alanine

Answer 7

Pyruvate

Question 8

Carbon skeleton of aspartate

Answer 8

Oxaloacetate

Question 9

Deamination

Answer 9

Removal of amino group from AA by lyases, dehydratases or dehydrogenases

Question 10

Products of deamination

Answer 10

Alpha keto acid and ammonia

Question 11

4 commonly delaminated AA

Answer 11

Glutamate

Histidine

Serine

Glycine

Question 12

What’s important about the products of deamination

Answer 12

Ammonia occurs in equilibrium with ammonium ion

Question 13

At normal physiological pH which is preferred?

Ammonium ion or ammonia

Answer 13

Ammonium ion

Question 14

What organ removes ammonia produced by deamination reaction

Answer 14

Liver

Question 15

Ammonia is toxic to what

Answer 15

Central nervous system

Question 16

Why is ammonia toxic to CNS

Answer 16

Ammonia reacts with alpha ketoglutarate to form glutamate. Which depletes the brain of alpha ketoglutarate

Question 17

What are some side effects of ammonia intoxication

Answer 17

tremor, slurred speech, blurred vision, coma, and death

Question 18

What are the 3 enzymes involved in ammonia disposal

Answer 18

Glutamate dehydrogenase

Glutamine synthetase

Carbomoyl phosphate synthase I (CPSI)

Question 19

What are the three substrates used by glutamate dehydrogenase

Answer 19

Uses NADPH, +NH4 and α-ketoglutarate

Question 20

What is the product of glutamate dehydrogenase reaction

Answer 20

Glutamate

Question 21

What are the three substrates used by glutamine synthetase

Answer 21

Uses ATP, glutamate, +NH4

Question 22

What is the product of glutamine synthetase reaction

Answer 22

Glutamine

Question 23

What is the product of CPSI

Answer 23

Carbomoyl phosphate

Question 24

What are the 4 substrates for CPSI reaction

Answer 24

ATP, ammonia, CO(2), N-Acetyl glutamate

Question 25

What is CPSI involved in

Answer 25

Urea cycle

Question 26

What is urea made of

Answer 26

Urea contains one nitrogen from ammonia and one from aspartate – the carbon comes from CO2 or HCO3-

Question 27

What is the effect of high protein diet and starvation on urea synthesis

Answer 27

Can increase synthesis of enzymes involved in urea cycle

Question 28

Glucagon and glucocorticoids effect on urea synthesis

Answer 28

Increase its activity

Question 29

What is the first intermediate in urea cycle? What does it combine with and what is the product?

Answer 29

Carbomoyl phosphate Ornithine Citrulline

Question 30

What is the primary regulator of urea cycle

Answer 30

Carbamoyl phosphate synthase I

Question 31

Activity of the CPS1 is determined by

Answer 31

N-acetylglutamate

Question 32

Low levels of NAG have what effect on urea cycle

Answer 32

Decrease activity

Question 33

Tyrosine is an important precursor for what?

Answer 33

Hormones, neurotransmitters, melanin, and thyroid hormones

Question 34

Characteristic of tyrosine

Answer 34

Both glucogenic and ketogenic

Question 35

Characteristic of methionine

Answer 35

Glucogenic

Question 36

Methionine yields

Answer 36

Succinyl- CoA

Question 37

What are the steps of metabolism of methionine

Answer 37

–Conversion to S-adenosyl methionine (SAM) by methionine adenosyl transferase –Demethylation of SAM by methyl transferase yields S-adenosyl homocysteine (SAH) –SAH hydrolase converts SAH to homocysteine

Question 38

Is homocysteine supposed to be in high amounts in the body

Answer 38

No

Question 39

What are the two ways homocysteine can be converted back to methionine

Answer 39

–Betaine-dependent reaction which forms glycine | –Vitamin B12-folate-dependent reaction

Question 40

What is another fate of homocysteine

Answer 40

Homocysteine can be further catabolized by cystathionine synthase and cystathionine lyase to form cysteine

Question 41

Why is SAM important

Answer 41

Methyl donor

Question 42

SAM primarily acts on?

Answer 42

DNA to change its gene expression

Question 43

What 4 things is SAM required for synthesis of?

Answer 43

carnitine, creatine, epinephrine, melatonin

Question 44

What is SAM effect on methionine

Answer 44

Promotes methionine catabolism by stimulating cystathionine synthase, which converts homocysteine to cystathionine

Question 45

What is SAM important for preventing

Answer 45

Homocysteine build up

Question 46

What are some risks of high homocysteine levels

Answer 46

–Blood clots •Coronary artery disease •Stroke –Dementia

Question 47

What are 4 cause of high homocysteine

Answer 47

–Defects in cystathionine synthase –Vitamin B6 deficiency –Vitamin B12 deficiency –Folate deficiency

Question 48

Where does degradation of phenylalanine occur

Answer 48

Primarily liver and kidneys

Question 49

Phenylalanine is catabolized to?

Answer 49

Tyrosine

Question 50

What hormone activates and inhibits phenylalanine

Answer 50

Glucagon activates Insulin inhibits

Question 51

Transamination

Answer 51

Transfer of an amino group from a AA to a α- keto acid (AA carbon skeleton)