Abstract
Mucopeptides extracted from Gram-positive cocci reacted with antisera against the synthetic random polypeptides poly (l-glu42-l-lys28-d-ala30)n and poly (d-glu16-l-lys16-dl-ala68)n. Quantitative precipitin inhibition studies employing a haptenic inhibitor derived from bacterial mucopeptide and synthetic peptides and polypeptides indicated that d-alanine is a critical amino acid in the antigenic determinant responsible for the cross-reactivity. Only copolymers containing d-alanine residues were effective inhibitors of the cross-reactivity.
The results of passive hemagglutination studies of appropriately coated erythrocytes and mucopeptide agglutination reactions with antimucopeptide sera and anti-synthetic polypeptide sera indicated that the immunologic relationship between bacterial mucopeptide and the synthetic copolymers of amino acids is predominantly associated with the presence of d-alanine in the determinant grouping.
Footnotes
This study was supported by National Institutes of Health Grants AM-AI-09846, AI-08429, AI-07825 and TI-AI-334, and by a Grant-in-Aid from the American Heart Association; it was conducted in part under the sponsorship of The Commission on Streptococcal and Staphylococcal Diseases, Armed Forces Epidemiology Board, and supported by the Office of the Surgeon General, Department of the Army, Washington, D. C.
