Pteroylpolyglutamate hydrolase of human granulocytes. I. Partial purification and kinetic studies

Abstract

Pteroylpolyglutamate hydrolase was demonstrated in the lysosome-like cytoplasmic granules of human granulocytes. Partial purification of this enzyme from granulocytes, obtained from patients with chronic myeloid leukaemia, was achieved by chromatography of the granule extract on Sephadex G-75, Bio-Rex 70 and hydroxylapatite. The enzyme preparation obtained was slightly contaminated with myeloperoxidase. Synthetic pteroyltetraglutamate was used as a substrate for the enzyme. The pH optimum was 5.1; the Km was 6 × 10^–3 mol/l; and the enzyme was activated by divalent cations, e.g. Ca⁺⁺, Mg⁺⁺ and Mn⁺⁺. Pteroylpolyglutamate hydrolase is suggested to be involved in the destruction of microorganisms in granulocytes during phagocytosis.

Key Words:

• y-carboxypeptidase
• folic acid conjugase
• leucocytes
• plasma