Willmott 1 protein structure

Question 1

Strong interactions

Answer 1

Covalent bonds: Shared pairs of electrons

Ionic bonds : Based on charge, Much less significant wrt molecules of life

Question 2

Weak interactions :

Answer 2

Hydrogen bonds: weaker than covalent (~1/20th), O & N = electro -/ve (straight line)
Van der Waals: Between all molecules, very weak Short distances (~3Å = 0.3 nm) (3-D shape)
Hydrophobic effect:

Question 3

HYDROPHOBIC EFFECT

Answer 3

-promotes folding hydrophobic in centre, hydrophilic on outer

Question 4

CHIRAL

Answer 4

non-superimposable mirror images

Question 5

CHEMICAL EQUILIBRIA:

Answer 5

A ⇔B reversible under fixed conditions
-Ration [A]:[B] constant: K=[products]/[reactants]
HA ⇔ H+ +A- (conjugate base & acid)

Question 6

Henderson-Hasselbalch equation

Answer 6

pK=-log Kd
pH=pK +log ([A-]/[HA])

pH=pK + log ([unprotonated]/[protonated])

Question 7

pK

Answer 7

measure of ease of dissociation of proton :
measure of pH when ionisable grp is 50% dissociated
lower number = stronger acid

Question 8

pH>pK basic which form is predominant?

Answer 8

form COO- predominant

Question 9

pH<pK acid which form is predominant?

Answer 9

COOH predominant

Question 10

What pK for COO- to be predominant?

Answer 10

COOH pK=~3 if

pH>7 COO- predominate

Question 11

What pK for NH3+ to be predominant?

Answer 11

NH2 grp pH=~8

NH3+ predominate

Question 12

zwitterion form:

Answer 12

at pH 7 amino & carboxyl grps are charged =dipolar