Grafting of a calcium-binding loop of thermolysin to Bacillus subtilis neutral protease.

The surface loop wich in the Bacillus subtilis neutral protease (NP) extends from amino acid residue 188 to residue 194 was replaced, by site-directed mutagenesis, with the 10-residue segment which in the homlogous polypeptide chain of thermolysin (TLN) binds calcium-4 The mutant NP was isolated to homogeneity, and its structural, functional, calcium-binding, and stability properties were investigated.