Subcellular distribution of amino acid naphthylamidase isozymes in human leucocytes.

Three isozymes (A, B and C) of amino acid naphthylamidase were found in human leucocytes. Isozyme B and C had close biochemical similarities and differed from isozyme A. Isozyme A was localized in the cytosol. Results obtained by combining electrophoresis with gradient centrifugation suggested that isozyme B originated in granules of polymorphonuclear leucocytes enriched in alkaline phosphatase. Isozyme C was found in granules of low density of polymorphonuclear as well as mononuclear leucocytes.