STRUCTURAL CHARACTERIZATION OF MOUSE MONOCLONAL-ANTIBODY-13-1 AGAINSTA PORPHYRIN DERIVATIVE - IDENTIFICATION OF A DISULFIDE BOND IN CDR-H3OF MAB13-1

The amino acid sequence of a mouse monoclonal antibody Mab13-1, a cata lytic antibody against TCPP (meso-tetrakis (4-carboxyphenyl)porphyrin) , was confirmed by mass spectrometric (MS) peptide mapping. The amino- terminal sequence of the heavy chain was established by MS/MS analysis of the isolated N-terminal peptide. The presence of a unique disulfid e bond between Cys93H and Cys102H was identified by MS peptide mapping and sequence analysis of an S-S containing peptide. Positions of othe r disulfide bonds were identified to be conserved. The non-conserved d isulfide bridge was found to be resistant as other intra-chain disulfi de bonds against reduction under non-denaturing condition, and to be b uried inside the molecule. This extra disulfide bond is expected to su pport antigen-binding by restricting the flexibility of CDR-H3 loop, a nd it might be favorable for the recognition of a plane antigen, a por phyrin derivative. (C) 1997 Academic Press.