Cleavage specificity of a myofibril-bound serine proteinase from carp (Cyprinus carpio) muscle

Previously, we reported the purification and characterization of a myofibri l-bound serine proteinase (MBP) from carp muscle (Osatomi K, Sasai H, Cao M -J, Hara K, Ishihara T. Comp Biochem Physiol 1997;116B:159-66). In the pres ent study, the N-terminal amino acid sequence of the enzyme was determined, which showed high identity with those of other trypsin-like serine proteas es. The cleavage specificity of MBP for dibasic and monobasic residues was investigated using various fluorogenic substrates and peptides. Analyses of the cleaved peptide products showed that the enzyme hydrolyzed peptides bo th at monobasic and dibasic amino acid residues. Monobasic amino acid resid ues were hydrolyzed at the carboxyl side; dibasic residues were cleaved eit her at the carboxyl side of the pair or between the two basic residues and the enzyme showed a cleavage preference for the Arg-Arg pair. Unexpectedly, MBP hydrolyzed lysyl-bradykinin and methionyl-lysyl-bradykinin at the carb oxyl side of Gly fairly specifically and efficiently displaying a unique cl eavage. Because MBP also degraded protein substrates such as casein and myo fibrillar proteins, the substrate specificity of MBP appeared not to be str ictly specific. (C) 1999 Elsevier Science Inc. All rights reserved.