Amino acid sequence of the Phaseolus vulgaris var. "fogo na serra" inhibitor and interactive surface modeling for the enzyme-inhibitor complex.

A trypsin and chymotrypsin inhibitor from seeds of Phaseolus vulgaris var. "Fogo na Serra" (PFSI) was purified and its complete amino acid sequence was determined using Edman degradation methods. The inhibitor was found to belong to the Bowman-Birk family of enzymatic inhibitors; it has 82 amino acid residues and a 8.985-kDa molecular mass. The PFSI/alpha-chymotrypsin binary complex has been modeled using the Turkey ovomucoid inhibitor third domain (OMTKY3) bound to alpha-chymotrypsin [Fujinaga et al. (1987), J. Mol. Biol., 195, 397-418. template. The model allowed identification of the binding surface.