Purification and characterization of recombinant pyrrolidone carboxyl peptidase of Bacillus subtilis

Bacillus subtilis pyrrolidone carboxyl peptidase (Pcp) overexpressed in Escherichia coli was purified to homogeneity in less than 12 h using ammonium sulphate precipitation and hydrophobic interaction chromatography. The enzyme, which removes amino-terminal L-pyroglutamic acid from peptides, appears to be a tetramer of 25,200 molecular mass subunits. The protein cross-reacted with polyclonal antibodies raised against Pcp from Streptococcus pyogenes. The overexpressed enzyme exhibits an absolute substrate specificity towards N-terminal pyroglutamyl residues with a Michaelis constant of 1.04 mM for L-pyroglutamyl-beta-naphthylamide. The enzyme could be used for the removal of pyroglutamyl residues that block amino termini of proteins and peptides before performing Edman sequential degradation.