Antibody to glucosyltransferase induced by synthetic peptides associated with catalytic regions of alpha-amylases.

We examined the immunogenicity and induction of inhibitory activity of 19-mer synthetic peptides which contained putative catalytic regions that were associated with the beta5 (EAW) and beta7 (HDS) strand elements of the suggested (beta,alpha)8 catalytic barrel domain of Streptococcus mutans glucosyltransferase (GTF). Both peptides readily induced serum immunoglobulin G (IgG) and salivary IgA antipeptide activity which was reactive both with the inciting peptide and with intact S. mutans GTF. Antisera to each peptide construct also inhibited the ability of S. mutans GTF to synthesize glucan. These observations support the existence of catalytic subdomains containing glutamate and tryptophan (EAW) or aspartate and histidine (HDS) residues, each of which have been suggested to be involved with the catalytic activity of GTF. Furthermore, the epitopes defined in these sequences have significant immunogenicity and can induce immune responses which interfere with GTF-mediated glucan synthesis.