Conjugation Guide

Conjugation Guide

There are 2 things to consider for conjugation:

1. Carrier protein (KLH, BSA, OVA, RSA)
2. Conjugation chemistry

• EDC, Activated EDC, MBS)
• EDC: Conjugates through carboxyl groups (let’s do this…)
• Activated EDC: Conjugates through free amines (let’s do this)
• MBS: Conjugates through the thiol group on cysteine

Steps for choosing conjugation method/chemistry:

1. Look for "D" or "E" residues. You should not use EDC if there are "D" or "E" residues.
2. Look for "K" residues. You should not use Activated EDC if there are "K" residues.
3. If the peptide has "D" or "E" residues but no "K", use Activated EDC to conjugate at the N-terminus.
4. If the peptide has "K" residues but no "D" or "E", use EDC to conjugate at the C-terminus.
5. If the peptide has "D", "E", and "K" residues, add a cysteine (C) to one end and conjugate using MBS.
6. If a peptide has "D" or "E", "K", and C residues, there is no way to get a single site of
conjugation at one end. You may consider changing the sequence. You are likely to get an immune response, even if there are multiple conjugation sites.
7. If you want the peptide conjugated at a specific end (N or C terminus), add a cysteine (C) on that side and conjugate using MBS.

Location of peptide segment within the native protein

• If the peptide segment is located at the N-terminal region of the native protein, conjugation should be done at the C-terminus of the peptide segment. This will allow the peptide segment to be in similar representation as the native protein.
• If the peptide segment is located at the C-terminal region of the native protein, conjugation should be done at the N-terminus of the peptide segment. This will allow the peptide segment to be in similar representation as the native protein.
  

If the peptide segment is located internally of the native protein, conjugation can be done at either end of the peptide segment.