Aminoacid as enegry

Question 1

What are the two classes of proteases and how do they cleave

Answer 1

Seqential cleavage at the peptide bodns by peptidases

exopeptidases: breaks of 1 2 or 3 amino acid lengths at the n or c term
n = aminopeptidases
c = carboxypeptidases

endopeptidases: breaks at specific sites in the middle of the peptide chain - specificity based of the left sidechain
pepsin + chymotrypsin - aromatic side chains
trypsin - postive charges

Question 2

How are proteases released and activated

Answer 2

Released as inactive pro enzymes of ogens, zymogens

activated:
autolytic - envionmental activation : pepsin + pH

catylytic - other enzyme activation/self activation: trypsin + enterokinase
trypsin -> all other pancratic proteases

Question 3

What are the 2 methods for deamination

Answer 3

1. amine group release
   - dehydrogenase cleves amine group using NADP coenzyme
   - leaves carbone skeleton + amino group (normally as NH4+)
2. Keto acid transfer
   aminotransferase uses PLP to transfer amino group to ketoacid -> leaves a different ketoacid + amino acid pair
   - amino acid amino group cleved -> PLP
   - PLP -> amino group to ketoacid

Question 3

How can amino acids and peptides be abosrbed

Answer 3

Only small peptides (di/tri) via H+/peptide co tranporters - cytosolic peptidases cleve to amino acids

amino acids via side chain specific amino acid carriers
- neutral
- basic + cycstine
- acidic
- proline/ hydroxy proline

Question 4

What are the properties of perioxal phosphate

Answer 4

Organic coenzyme VB6 derivitive
- carrys an amine group
- 2 states: perioxamine phosphate + perioxal phosphate

Question 5

What are 3 common keto acid amino acid pairs

Answer 5

Keto - amino

alpha ketoglutaric -> glutamate
pyruvate -> alanine
oxaloacetate -> aspargnine

Question 6

How can amino acids then be used as fuel

Answer 6

After deamination the ketoacids can be fed into metabolic pathways

Either into the CAC or into other pathways such as pyruvate into PDH reactions

Question 7

How is NH4 released from the body

Answer 7

NH4 = toxic -> removed via liver
Regnativive cycle
muscle: amino acid breaks to NH4 -
a-ketoglutarate -> glutamate reverse as pyruvate -> alaine

Alanine travels in blood to liver

liver: Alanine -> pyruvate as a-ketoglutarate -> glutamate : reaction reversed as NH4 release and turned to urea

liver Pyruvate -> glucose -> travel in blood to tissue -> glucose -> pyruvate