Aminoacid as enegry Flashcards
What are the two classes of proteases and how do they cleave
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
How are proteases released and activated
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
What are the 2 methods for deamination
- amine group release
- dehydrogenase cleves amine group using NADP coenzyme
- leaves carbone skeleton + amino group (normally as NH4+) - 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
How can amino acids and peptides be abosrbed
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
What are the properties of perioxal phosphate
Organic coenzyme VB6 derivitive
- carrys an amine group
- 2 states: perioxamine phosphate + perioxal phosphate
What are 3 common keto acid amino acid pairs
Keto - amino
alpha ketoglutaric -> glutamate
pyruvate -> alanine
oxaloacetate -> aspargnine
How can amino acids then be used as fuel
After deamination the ketoacids can be fed into metabolic pathways
Either into the CAC or into other pathways such as pyruvate into PDH reactions
How is NH4 released from the body
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