A phosphatase from chlorella dephosphorylating 3′-phosphoadenosine-5′-phosphosulfate to adenosine-5′-phosphosulfate

Abstract

A phosphatase was purified 312-fold from Chlorella extracts by trichloroacetic acid precipitation and subsequent separation on CM-cellulose and Sephadex-G-100 colun chromatography. Its molecular weight was determined on a Sephadex G-100 column to be about 57 000. This enzyme is capable of releasing phosphate from 2′-AMP, 3′-AMP, 5′-AMP, 3′-5′-ADP and 3′-phosphoadenosine-5′-phosphate (PAPS); thus it is nonspecific with respect to the position of the phosphate group. This enzyme was active without added magnesium ions and it was not inhibited by calcium ions, which distinguishes it from the 3′(2′),5′-diphosphonucleoside-3′(2′)-phosphohydrolyase of the same organism which is thought to be necessary to dephosphorylate PAPS to APS. The apparent K m data are: 1, 1.1 mM for 5′-AMP; 2, 0.9 mM for 3′-AMP; 3, 1.0 mM for 2′-AMP; 4, 4.7 mM for 3′-5′-ADP; and 5, 4.0 mM for PAPS.