Protein metabolism 1

Question 1

4,Hydroxyproline role in collagen stability

Answer 1

interstrand H bonding

Question 2

5,Hydroxylysine role in collagen stability

Answer 2

interstrand covalent bonding

Question 3

hydroxyproline formation enzyme

Answer 3

prolyl hydroxylase

Question 4

hydroxylysine formation enzyme

Answer 4

lysyl hydroxylase

Question 5

scurvy

Answer 5

Vit C deficiency. VC required for hydroxylation of proline and lysine.

• reduced collagen stability
• sunken eyes, pallor, bruising, tooth loss, hemorrhage and anemia

Question 6

Gamma-carboxyglutamate (Gla)

Answer 6

targets proteins to membrane via Ca chelation
-glutamyl carboxylase converts glutamate to Gla
Vit K cofactor

Question 7

Ubiquitin-proteosome degradation

Answer 7

ATP-dependent process cross-linking proteins with ubiquitin

• linked to protein via lysine AA
• targeted to proteosome, where it is degraded
• polyubiquinated proteins can act as signaling molecules

Question 8

Lysosomal path

Answer 8

Non-ATP-dependent process.

protein degraded by enzymes w/in phagocytic cells

Question 9

stomach protease (aspartic)

Answer 9

Pepsinogen activated by HCl to pepsin
Trypsinogen activated by enteropepsidase to trypsin
Chymotrypsinogen activated by trypsin to chymotrypsin

Question 10

Intestinal proteases (Serine & metallo)

Answer 10

Trypsinogen activated by enteropepsidase to trypsin
Chymotrypsinogen activated by trypsin to chymotrypsin
Carboxypeptidase A & B

Question 11

ALT

Answer 11

In Liver

Alanine to pyruvate

Question 12

AST

Answer 12

Aspartate to oxaloacetate

Question 13

Transamination

Answer 13

converts alpha ketoacid to AA and an AA to an alpha ketoacid

Keq=1, so reversible, non-energy-requiring reactions

Question 14

Pyridoxal phosphate (PLP)

Answer 14

Made from dietary vitamin B6

used to hold amino groups during transamination reactions via Schiff base