Proteins

Question 1

Endopeptidases or endoproteases catalyse

Answer 1

The hydrolysis of peptide bonds within a polypeptide.

They are usually specific

Act before exos

Question 2

Peptides are biologically synthesised from the _______ terminus to the _______ terminus

Answer 2

Amino to carboxy

Question 3

Carboxypeptidases catalyse….

Answer 3

The hydrolysis of the carboxy terminus peptide bond on a peptide chain

Question 4

Aminopeptidases catalyse…..

Answer 4

The hydrolysis of the amino terminus peptide bond on a peptide chain

Question 5

Disulphides bonds in a peptide are formed in peptides with ………… Residues. The are mainly found in ……….. Proteins

Answer 5

Cysteine residues, extracellular proteins

Question 6

Peptide bonds are ussually in the …… Conformation. Due to the double bond the peptide bond can exist in a ……. Form

Answer 6

Trans conformation, resonance form

Question 7

What is an isopeptide bond?

Answer 7

A bond formed between the side chain of Lysine and:

R groups of Asp, Glu, Asn and Gln,

An internal peptide bond or.

Terminal a-carboxyl terminus.

Question 8

Selenium can replace the sulphur in cysteine and methionine to form……………

Which of these effects protein function

Answer 8

Selenomethionine (Sem) and Selenocysteine (Sec)

Sec does

Question 9

Exopeptidases or exoproteases catalyse…

Answer 9

The hydrolysis of either the amino- or carboxy- terminus peptide bond.

Work from the ends inwards and are not specific

Act after endos

Question 10

What is Phosphorylation of proteins

Answer 10

The addition of a phosphate group from ATP to an OH group on an amino acid

Needs protein kinase

Question 11

Ser/thr kinases do what

Answer 11

Phosphorylate either Serine or Threonine

Question 12

Phosphates does what

Answer 12

Removes a phosphoryl group

Question 13

Farnesylation is the formation of a ………… Bond between farnesylpyrophosphate and cysteine

Answer 13

Thioester bond

Question 14

Myristoylation is the formation of an ……… Bond between myristoyl CoA and an amine group

Answer 14

Amide bond

Question 15

Palmitoylation is the formation of a ………. Bond between palmitoyl CoA and cysteine

Answer 15

Thioester bond

Question 16

Acetylation can occur on the ………. Terminus or on the side chain amino groups of ……… Residues

Answer 16

Amino terminus or amino groups on Lysine side chains