Peptidyl-Asp metalloendopeptidase

This chapter covers the structural chemistry and the biological aspects of peptidyl-Asp metalloendopeptidase. Peptidyl-Asp metalloendopeptidase was first isolated from the culture supernatant of Pseudomonas fragi. Peptidyl-Asp metalloendopeptidase specifically cleaves peptide bonds at the N-terminal side of either aspartic acid (Xaa-Asp) or cysteic acid residues (Xaa-Cya). Partial amino acid sequences have been determined by Edman sequencing of the enzyme. They match very well to the two sequences derived from the genome of two Xanthomonas strains. The sequence contains a HEXXH pattern, which is a potential zinc-binding site. It is then placed in a new family M72 by MEROPS. Peptidyl-Asp metalloendopeptidase is a single-chain protein with a relative molecular mass of 24,440 as determined by laser-desorption mass spectrometry. On SDS gels, a single band with a relative molecular mass of 27,000 is found. Purification of peptidyl-Asp metalloendoproteinase from a Pseudomonas fragi mutant is described by Noreau & Drapeau (1979). However, for its application in protein sequencing, peptidyl-Asp metalloendopeptidase may have to be further purified by ion-exchange chromatography.