MOUSE LYMPHOCYTE ENZYMATIC MARKERS - A RAPID METHOD FOR ACHIEVING SELECTIVE SOLUBILIZATION AND EFFICIENT RECOVERY OF THE MEMBRANE-BOUND 5'-NUCLEOTIDASE

A simple method is described for achieving a good recovery and a partial purification of the membrane-bound 5′-nucleotidase (5′-N) from mouse lymphocytes. The experimental procedure is based upon plasma membrane isolation on polycationic beads and selective solubilization of the enzyme activity from bead-bound plasma membranes. With this method, more than 95% of the 5′-N activity detectable in the whole cell homogenates can be routinely recovered in a single fraction showing a 5′-N specific activity which is at least 60 times higher than that found in the crude homogenate. This method also provides a complete separation of 5′-N from the membrane-bound alkaline phosphatase (AP), as well as from any other interfering non-specific phosphatase. Since this method is rapid and highly reproducible even when small amounts of lymphocytes are available, it may be useful for detecting changes in 5′-N activity in the different T- and B-lymphocyte subpopulations.