Cofactors

Question 1

How can functionality be added to a protein beyond the ribosomally incorporated amino acids?

Answer 1

• Metal ions: metalloproteins (zinc, iron, copper)
• Organo-metallic cofactors (heme group, iron-sulfur clusters, chlorophyl)
• organic cofactors (phosphopantetheine, biotin, pyridoxal phosphate, lipoic acid, FAD)
• Fatty acids (myristoylation in recoverin)
• Covalently modify specific amino acid sidechains.

Question 2

Name some proteins which could not function without their cofactor.

Answer 2

• DaAT
• myoglobin
• cytochrome c
  -PQQ bound to polyamine oxidase

Question 3

Give examples of co-translational protein modification

Answer 3

• metal ions
• heme group
• iron-sulfur cluster
• chlorophyl
• pyridoxal phosphate

Question 4

give examples of post-translational protein modification

Answer 4

Phosphorylated and dephosphorylation.

Question 5

Define cofactor

Answer 5

any non-protein chemical compound that is required for the biological activity of a protein.

Question 6

Define Prosthetic group

Answer 6

A covalently attached, or extremely well held cofactor

Question 7

Define coenzyme

Answer 7

A loosely held cofactor which dissociates on and off the enzyme.