[Trypsin and chymotrypsin inhibitors in leguminosae VII. Partial amino acid sequences of the trypsin chymotrypsin inhibitor PCI 3 from Phaseolus coccineus (author's transl)].

The sequences of amino acid residues at the amino and carboxyl terminus and around the reactive sites of the trypsin chymotrypsin inhibitor PCI 3 from the seeds of runner beans (Phaseolus coccineus L.) were estimated by aminopeptidase O and carbosypeptidase A degradation before and after enzymatical modification with trypsin or chymotrypsin. Beginning at the amino terminus the sequences are :Ser-Glu-Ala-Gly-Gln-...,...-Ile-Tyr-Lys-Ser-Gln-(Pro)-...with Lys-Ser as reactive site against trypsin, ...-Asp-Val-Ala-Leu-Ser-(Pro)-...with Leu-Ser as reactive site against alpha-chymotrypsin, and ...-Thr-Arg-Ala-Lys-Phe-Leu as C-terminus. The importance of the serine residue in the reactive sites concerning the specificity of inhibitors is discussed.