Lecture 31: aa catabolism

Question 1

what type of reaction is oxidoreductases?

Answer 1

oxidation-reduction

Question 2

What type of reaction is transferases?

Answer 2

group transfer

Question 3

What type of reaction is hydrolases?

Answer 3

hydrolysis reactions (transfer of functional groups to water)

Question 4

What are the two structures cells have that degrade proteins?

Answer 4

proteasome

lysosome

Question 5

What is the N-end rule?

Answer 5

N terminal amino acid identity determines rate of ubiquitination

Question 6

What is ubiquitin?

Answer 6

proteins that binds to proteasome

Question 7

What is the proteasome?

Answer 7

an ATPase
20s piece is catalytic/proteolytic domain
19s piece is the regulatory domain

Question 8

What can you do with individual amino acids?

Answer 8

dispose of nitrogen through urea cycle
make new proteins
repurpose the carbon skeletons

Question 9

Describe direct deamination (serine and threonine only)

Answer 9

remove H20=dehydration
add H20 back to remove NH4+ deamination
serine is deaminated to form pyruvate
throne is deaminated to form a-ketobutyrate

Question 10

what does it mean if amino acids are glucogenic?

Answer 10

degraded into intermediate molecules that can feed through gluconeogenesis to reform glucose

Question 11

what does it mean if amino acids are ketogenic?

Answer 11

degraded into intermediate molecules that can be sued to create ketone bodies

Question 12

What is the fate of serine when converted to pyruvate?

Answer 12

deaminated directly to pyruvate

Question 13

What is the fate of threonine when converted to pyruvate?

Answer 13

converted to glycine after deamination

Question 14

What is the fate of glycine when converted to pyruvate?

Answer 14

converted to serine in a THF-dependent reaction

Question 15

What is the fate of alanine when converted to pyruvate?

Answer 15

enhanced with pyruvate by the action of SGPT

Question 16

What is the fate of cysteine when converted to pyruvate?

Answer 16

must be deaminated and desulfonated to form pyruvate

Question 17

What is the fate of asparagine when converted to oxaloacetate?

Answer 17

deaminated first from the side chain to form NH4+ and aspartate

Question 18

What is the fate of aspartate when converted to oxaloactate?

Answer 18

exchanged with oxaloactate by the action of SGOT

Question 19

What is the fate of glutamine when converted to alpha-ketoglutarate?

Answer 19

deaminated first from the side chain to form NH4+ and glutamate

Question 20

What is the fate of proline, arginine, and histidine when converted to alpha-ketoglutarate?

Answer 20

can all be converted to glutamate

Question 21

What is the fate of glutamate when converted to alpha-ketoglutarate?

Answer 21

converted alpha ketoglutarate by glutamate dehydrogenase

Question 22

What is the fate of methionine, valine and isoleucine when converted to succinyl-CoA

Answer 22

converted into propionyl-CoA in B12 dependent pathway.

Question 23

glycogenic only amino acids

Answer 23

alanine
arginine
asparagine
aparatate
cysteine
glycine
glutamate
glutamine
histidine 
methionine
serine
valine
proline

Question 24

ketogenic only amino acids

Answer 24

leucine

lysine

Question 25

glucogenic and ketogenic

Answer 25

isoleucine 
phenylalanien 
threonine
tryptophan
tyrosine