C-terminal antibodies (CTAbs): a simple and broadly applicable approach for the rapid generation of protein-specific antibodies with predefined specificity.

Recent advances in proteomic techniques have resulted in an ever-increasing need to produce antibodies. Here, to address this problem, a technically simple approach of targeting the extreme C-termini of proteins with antibodies (CTAbs) was investigated in proteins secreted by the human pathogen Streptococcus pyogenes. Target proteins were identified by a conventional proteomic approach and CTAbs produced against synthetic five amino acid peptides representing the C-terminus of each target protein. In every case where protein secretion was demonstrated (n = 20), CTAbs were successfully produced and bound specifically to the target protein (100% success rate). The apparent specificity was consistent with the structural heterogeneity of the C-termini of S. pyogenes proteins. The global specificity of CTAb binding was defined using a combinatorial library of synthetic peptides representing structural variants of the original synthetic immunogen. This is a systematic and comprehensive approach for the development of antibodies with defined specificity that can be used in a range of applications.