Effect of peptide acetylation on its interaction with antipeptide antibody.

The effects of trace acetylation on the contact sites in peptide-antibody binding have been investigated by using a label selection method. A 13-residue synthetic peptide having three lysines (LKLVEQQNPKVKL) corresponding to sequence position 155-168 of beta 1,4-galactosyltransferase was used in this study. The four amino groups located throughout the peptide sequence, labeled appropriately, served as probing marker groups. The amino terminus region of the peptide was highly reactive to trace acetylation. Over 80% of the label appeared in the amino terminus region, most likely in the alpha-amino group due to its lower pK value. Interestingly, acetylation of Lys10 and Lys12 (carboxy terminal region) showed a selection for interacting with the antibody. This approach, using label selection affords high sensitivity and could be applicable for mapping antigen-antibody interaction site/s.