Heteroclitic recognition of combinatorial TX 1 TX 2 T peptide mixtures by mucin‐2 protein specific monoclonal antibody

• Published in: Journal of peptide science 2004-01, Vol.10 (1), p.56-65
• Main Authors: Windberg, Emôke, Uray, Katalin, Illyés, Eszter, Skribanek, Zsolt, Price, Michael R., Sebestyén, Ferenc, Hudecz, Ferenc
• Format: Article
• Language: English
• ISSN: 1075-2617; 1099-1387
• DOI: 10.1002/psc.483

The mucin‐2 (MUC2) glycoprotein secreted by the epithelial cells of human colon may be abnormally under‐glycosylated in the case of cancer. Monoclonal antibody (mAb) 994 raised against the immunogenic part of the protein core, recognizes malignant human colon tissues as well as pentapeptides with TX 1 TX 2 T motif present in MUC2. Using a combinatorial approach and ELISA experiments it was found that mAb 994 is able to recognize peptides of the sub‐library TQTX 2 T very strongly, and to some extent also peptides from TETX 2 T, TLTX 2 T and TVTX 2 T sub‐libraries. Binding studies with peptides corresponding to the TQTX 2 T and TETX 2 T sub‐libraries showed that mAb 994 recognized only six peptides (IC 50 = 9–208 µmol dm −3 ) from the 19 compounds of the TQTX 2 T sub‐library and only three peptides (IC 50 = 3500–16700 µmol dm −3 ) from the ‘second‐best’ TETX 2 T sub‐library. The most pronounced mAb binding occurred when Gln was in position X 1 and it was much weaker in the case of Glu, Val or Leu. As for X 2 amino acids, the presence of Pro, Ala can provide a strong, while Tyr, Trp, Phe and Ser a weaker, peptide–antibody interaction. Data from this study suggest that pentapeptide TQTPT, whose sequence is present in the native protein, is bound most strongly. However, almost identical binding properties were observed with peptide TQTAT, whose sequence is not present in the protein. Apart from this, some other ‘heteroclitic’ peptides were found with a different rank in the binding‐hierarchy. Based on these peptides artificial compounds can be prepared as potential candidates for vaccine development. Results of this study also provide a rationale for understanding the molecular background of the heteroclitic nature of the MUC2 protein core specific mAb 994. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.