Peptide Bonds & Protein Structure

Which two functional groups react to form a peptide bond?

The carboxyl group and amino group.

What type of bond is a peptide bond?

An amide bond and a covalent bond linking two amino acids.

How many amino-acid residues are required for a peptide chain to qualify as a polypeptide according to the review?

At least 20 amino acids.

What is a peptide containing 2 amino acids called?

A dipeptide.

What is a peptide containing 3 amino acids called?

A tripeptide.

What is a peptide containing 4–20 amino acids called?

An oligopeptide.

What two termini are present in a peptide chain?

The N-terminus and C-terminus.

Which terminus is at the beginning of a peptide chain?

The amino/N-terminus.

Which terminus is at the end of a peptide chain?

The carboxyl/C-terminus.

What memory aid is given for the N-terminus?

N = begiNning.

What memory aid is given for the C-terminus?

C = end/ConClusion.

True or false: A peptide bond is a double bond.

False.

Why can a peptide bond not freely rotate even though it is not a true double bond?

It has double-bond character due to resonance.

What torsional angle corresponds to the alpha carbon-carboxyl bond?

Psi (ψ).

What torsional angle corresponds to the alpha carbon-amino bond?

Phi (φ).

What memory aid is given for Psi?

C, C = PSI.