B.2. Proteins and Enzymes

Question 1

All amino acids except glysine have what?

Answer 1

2-carbon atom that is a chiral carbon

glysine has H=R

Question 2

As a result of zwitterions what state and form do amino acids exist in?

Answer 2

As result of electrostatic forces betw/ the zwitterions

→ form crystalline solid w/ high mp

Question 3

Why are amino acids much more soluble in water than in non-polar solvents?

Answer 3

The presence of ions allow bonding w/ polar water molecules

Question 4

As the non-polar R group gets larger what happens to solubility?

Answer 4

Less soluble in water

Question 5

What is the bond formed from condensation reactions of aa?

Answer 5

peptide bond/linkage

Question 6

When forming condensation reactions, by convention where are the 2 functional groups?

Answer 6

+ Terminal amino-group one the RHS

+ Terminal carboxylic acid group on the LHS

Question 7

Peptide chains can undergo hydrolysis in the presence of what?

Answer 7

Strong acid
Strong base
Enzymes

Question 8

Primary structure of protein

Answer 8

How the aa’s stringed together

Question 9

Secondary structure of protein

Answer 9

How the polypeptide chain or aa folds itself

Question 10

α-helix

Answer 10

InTRA-chain hydrogen bonding
+ Due to regular H-bonds between (δ-) oxygen of -C=O and the (δ+) hydrogen of the NH2- group
+ 4 AMINO ACIDS DOWN THE CHAIN

Question 11

Examples of α-helix proteins

Answer 11

+ Fibrous protein elastic or sponge

+ Hair or wool

Question 12

β-pleated sheets

Answer 12

InTER-chain hydrogen bonding
+ polypeptide chains and the aa’s have rather small side chains
+ CHAINS are bound together by H.bond
+ orderly alignment or polypeptide chains arranges side to side
+ direction of H.bond = perpendicular to chain

Question 13

Example of β-pleated sheets

Answer 13

+ Fibrous protein = Silk