AA breakdown

Question 1

two main themes of AA catabolism

Answer 1

catabolism of amino groups (N theme)
catabolism of carbon skeletons (C theme)

Question 2

catabolism of amino groups (N theme)

Answer 2

amino group deamination> detoxification of ammonia

Question 3

catabolism of carbon groups (C theme)

Answer 3

broken down to critic acid cycle intermediates> 20 dif pathways

Question 4

enzymatic degradation of dietary proteins

Answer 4

starts in stomach
-polypeptide chains broken into smaller peptides

small intestinie
-free AA transported through epithelial cells and anter blood capilaries to travel to liver

Question 5

essenstial AA

Answer 5

nine and must be broken down from protein in our diet

Question 6

when is protein broken down

Answer 6

during protein turnover or when carb fuel not availabel

Question 7

what happens when amine group is separated during metabolism (as ammonia)

Answer 7

it can be toxic to the cell

Question 8

what must happen to prevent amomonia toxicity

Answer 8

1. ammonia must be removed from AA
2. ammonia must be sent to liver to be metabolized into less toxic substance (urea)

Question 9

where does glutamine come from

Answer 9

muscle and other tissues

Question 10

where does alanine come from

Answer 10

muscle

Question 11

energy of transamination reactions

Answer 11

reversible and delta G is zero

Question 12

what do transaminases do

Answer 12

move Amino group from AA to keto acid (a ketoglutarate)

require a cofactor pyridoxine (vit B6)

Question 13

what shuttle relies on transaminases

Answer 13

malata aspartate shuttle

Question 14

differences bw transaminases

Answer 14

differ in specificity for the L amino acid

• many specific for a ketoglutarate as amino group acceptor
  -reactions effectively collect amino groups from many AA in the form of L glutamate

Question 15

PLP long version

Answer 15

pyridoxine/ pyridoxal phosphate

Question 16

PLP, what is it and what does it do

Answer 16

used as prosthetic group by all aminotransferases
carries amino groups to active site
transfers amino group to a-keto acid

Question 17

PLP and other enzymes

Answer 17

transamination
racemization
decarboxylation

Question 18

what does glutamate release its amino group as and where

Answer 18

ammonia in the liver

Question 19

wehre does NH4 in the mitochondria come from

Answer 19

many different a-amino acids in the form of amino group of L-glutamate or amide nitrogen of glutamine

Question 20

glutamate oxaditative deamination

Answer 20

doesnt have to transfer its nitrogen group bc it can undergo oxidative deamination in the mitochondrial matrix as ammonia in the cytoplasm woudl damage cell

this rxn is catalyzed by L-glutamate dehydrogenase

Question 21

what does L glutamate dehydrogenase use

Answer 21

NAD+

Question 22

L glutamate dehydrogenase

Answer 22

produces a-ketoglutarate to enter CAC or glucose synthesis
produces NH4 to enter urea cycle

Question 23

transdeamination

Answer 23

overal reaction of transmination and glytamate dehydrogenase