Purification and Properties of 5′‐Nucleotidase from Lymphocyte Plasma Membranes

Abstract

5''-Nucleotidase [EC 3.1.3.5] is purified from [pig] lymphocyte plasma membranes by 2 affinity chromatographies. The 1st one, on Lens culinaris lectin-Sepharose 4B yields a fraction of 12 lectin-binding glycoproteins (lectin-receptor fraction). The 2nd one on 5''-AMP-Sepharose 4B leads to pure enzyme. This enzyme is a glycoprotein with a MW of 130,000; it gives a single band in polyacrylamide/dodecylsulfate electrophoresis and displays a very high specific activity (2500-3000 .mu.mol Pi h-1 mg-1). Some properties of purified 5''-nucleotidase are similar to those of membrane-bound enzyme:substrate specificity, temperature dependence, effects of ions and SH-blocking reagents. Others are completely different for the 2 systems and these differences result from an interaction between the enzyme molecule and other L. culinaris lectin binding proteins.