Sulfur and Aromatic AA Metabolism

Question 1

Name 3 major products that Trp is used to make.

Answer 1

1. serotonin
2. melatonin
3. niacin

Question 2

Where are Met residues usually found?

Answer 2

in the center of the protein

Question 3

What aa is used to produce S-adenosylmethionine (SAM), a high energy storage unit?

Answer 3

methionine

Question 4

How is hyperhomocysteinemia treated?

Answer 4

• folate
• B6
• B12

Question 5

_____ is hydroxylated by phenylalanaine hydroxylase to produce Tyr using BH4 as a cofactor.

Answer 5

Phe

Question 6

What is unique about cysteine?

Answer 6

it can form disulfide bonds –> strength

Question 7

What is cysteinuria?

Answer 7

kidney stones –> renal failure due to defective cysteine transporter –> crystallization in urea

Question 8

What is a tyrosinemia?

Answer 8

a defect in tyrosine degradation

Question 9

Is methionine essential?

Answer 9

yes

Question 10

Phe and Tyr are metabolized to _____ or ______.

Answer 10

• fumarate
• acetoacetate

Question 11

What are the 2 sulfur containing aa’s?

Answer 11

1. methionine
2. cysteine

Question 12

Phe is hydroxylated by phenylalanaine hydroxylase to produce _____ using BH4 as a cofactor.

Answer 12

Tyr

Question 13

What can elevated homocysteine lead to?

Answer 13

• vascular disease
• impaired wound healing
• CA

Question 14

What is the tx for homocystinuria?

Answer 14

vitamin B6

Question 15

Trp is metabolized to ____ or _____.

Answer 15

• pyruvate
• acetyl-CoA

Question 16

_____ is metabolized to pyruvate or acetyl-CoA.

Answer 16

Trp

Question 17

Tyr is hydroxylated by ______ to produce DOPA using BH4.

Answer 17

tyrosine hydroxylase

Question 18

What is S-adenosylmethionine (SAM) used for?

Answer 18

• methylation (DNA, proteins, NE–>epi)
• epigenetics
• host defense
• CA development
• fetal development
• tx for depression

Question 19

_____ is hydroxylated by tyrosine hydroxylase to produce DOPA using BH4.

Answer 19

Tyr

Question 20

This is a defect in phenylalanine hydroxylase –> build up of alternate byproducts (phenylacetate, phenylpyruvate).

Answer 20

phenylketonuria (PKU)

Question 21

This disease causes kidney stones –> renal failure due to defective cysteine transporter –> crystallization in urea.

Answer 21

cysteinuria

Question 22

What is tetrahydrofolate (THF) synthesized from?

Answer 22

vitamin B9 (folic acid)

Question 23

What aa can form disulfide bonds?

Answer 23

cysteine

Question 24

Phe is hydroxylated by ______ to produce Tyr using BH4 as a cofactor.

Answer 24

phenylalanaine hydroxylase

Question 25

DOPA can be metabolized into _____ and \_\_\_\_\_.

Answer 25

* catecholamines (DOPA, DA, NE, epi) * melanin

Question 26

Where are Cys residues typically found?

Answer 26

in the active site

Question 27

What is phenylketonuria (PKU)?

Answer 27

a defect in phenylalanine hydroxylase --\> build up of alternate byproducts (phenylacetate, phenylpyruvate)

Question 28

What is hyperhomocysteinemia?

Answer 28

elevated levels of homocysteine (bad)

Question 29

This is a defect in cystathione-b-synthase (CBS) so homocysteine cannot be converted to cystathione --\> mental retardation, osteoporosis, vascular disease.

Answer 29

homocystinuria

Question 30

Name 3 aromatic aa's.

Answer 30

1. tryptophan 2. phenylalanine 3. tyrosine

Question 31

What is homocystinuria?

Answer 31

a defect in cystathione-b-synthase (CBS) so homocysteine cannot be converted to cystathione --\> mental retardation, osteoporosis, vascular disease

Question 32

Is cysteine essential?

Answer 32

no

Question 33

What is a cofactor for trp hydroxylation?

Answer 33

tetrahydrobiopterin (BH4)

Question 34

\_\_\_ and ____ are metabolized to fumarate or acetoacetate.

Answer 34

* Phe * Tyr

Question 35

Tyr is hydroxylated by tyrosine hydroxylase to produce _____ using BH4.

Answer 35

DOPA

Question 36

What is required for the converstion of homocysteine --\> methionine?

Answer 36

* THF * vitamin B12

Question 37

This peptide's functions include: * it allows for proper folding and disulfide bond formation * a redox buffer * a cofactor * protects against ROS

Answer 37

glutathione (GSH)

Question 38

What is unique about methionine?

Answer 38

it's used to produce S-adenosylmethionine (SAM) --\> high energy storage unit

Question 39

What is the tx for cysteinuria?

Answer 39

acetazolamide

Question 40

What is the function of glutathione (GSH)?

Answer 40

* it allows for proper folding and disulfide bond formation * a redox buffer * a cofactor * protects against ROS

Question 41

What is the term for elevated levels of homocysteine?

Answer 41

hyperhomocysteinemia