Characterization of 2′:3′‐Cyclic Nucleotide 3′‐Phosphodiesterase: Limited Proteolytic Digestion, Plant Lectin Affinity Chromatography, and Immunological Identification

Abstract

Purified bovine brain 2':3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) migrates as a protein double band in SDS-polyacrylamide gel electrophoresis. The positions of the two protein bands correspond to approximate molecular weights (MW) of 56,000 and 53,000. Limited protease treatment of isolated CNPase leads to subsequent degradation of the enzyme into smaller polypeptides having MWs of approximately 40,000, 30,000, and 20,000. During proteolytic digestion CNPase remains enzymatically active. Binding studies with several immobilized plant lectins as well as periodic acid-Schiff reagent (PAS) staining of SDS gels indicate that CNPase is a glycoprotein. An antiserum against purified CNPase, prepared in rabbits, was used to confirm the immunological identity of various CNPase preparations obtained in our laboratory.