Proteins

Question 1

4 properties of peptide bonds

Answer 1

1) rigid bond - there is one double bonds which restricts rotation of atoms around the bond.
2) all peptide bonds are in planar
3) All exhibit trans isomers
4) Made through condensation reactions.

Question 2

Define pka value

Answer 2

• how likely an amino acid will ionise

Question 3

What will be the predominant form of a protein if the pH is greater than the pka value ?

Answer 3

• more basic as there are fewer h+ ions

- Eq will shift to the deprotonated form of the protein.

Question 4

Define isoelectric point

Answer 4

The ph at which a protein has no overall charge

Question 5

What happens if the isoelectric point is greater than 7?

Answer 5

• the protein is basic as they have positively charged amino acids

Question 6

What are the forces involved in maintaining protein structure?

Answer 6

1) dislufide bridges between cysteine amino acid residues.
2) ionic bonds between charged amino acid residues.
3) hydrogen bonds between -HO , NH, FH
4) van deer waals between all residues
5) hydrophobic interactions between non polar molecules
6) hydrophilic interactions between polar molecules