Lecture 5

Question 1

What are the positive side chains

Answer 1

Lysine, histidine , arginine

Question 2

What is the Pi

Answer 2

Isoelectric point-pH at which molecule or surface has no net charge

Question 3

What aa’s are in the R aromatic group

Answer 3

Phenylalanine, tyrosine and tryptophan

Question 4

What is a residue

Answer 4

The part of the amino acid that remains after a peptide bond is formed

Question 5

What is the typical pKa of a terminal a-carboxyl group

Answer 5

3.1

Question 6

What is the typical pKa of an aspartic or glutamic acid side chain

Answer 6

4.1

Question 7

What is the typical pKa of a histidine sidechain

Answer 7

6

Question 8

What is the typical pKa of a terminal a-amino group

Answer 8

8

Question 9

What is the typical pKa of a cysteine side chain

Answer 9

8.3

Question 10

What is the typical pKa of a tyrosine side chain

Answer 10

10.9

Question 11

What is the typical pKa of a lysine side chain

Answer 11

10.8

Question 12

What is the typical pKa of an arginine side chain

Answer 12

12.5

Question 13

What is an amino acid with 2 carboxylic groups

Answer 13

Asp

Question 14

When the pI is less than the pH what charge will there be

Answer 14

A positive net charge

Question 15

Why is a peptide bond planar

Answer 15

Because it has partial double bond character , preventing rotation

Question 16

What does dihydrofolate reductase (DHFR) do

Answer 16

I converts dihydrofolate to tetrahydrofolate (NADPH is the coenzyme)

Question 17

Why is dihydrofolate reductase important

Answer 17

Important in one carbon metabolism eg synthesis of nucleus acids. Also important I’m cancer chemotherapies.

Question 18

Name 2 important chemotherapy drugs

Answer 18

Methotrexate and trimethoporin

Question 19

2 examples of chemical denaturants for unfolding of Ribonuclease a

Answer 19

Urea and guanidium chloride