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Purification and characterization of the plasmodial phosphatase that hydrolyses the phosphorylated light chain of Physarum myosin II from Physarum polycephalum
Author(s) -
Okada Chisa,
Nakamura Akio,
Tomioka Shigeo,
Kohama Kazuhiro,
Kaneko Takako S.
Publication year - 2010
Publication title -
cell biology international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 77
eISSN - 1095-8355
pISSN - 1065-6995
DOI - 10.1042/cbi20090340
Subject(s) - physarum polycephalum , physarum , enzyme , dephosphorylation , biochemistry , myosin , hydrolysis , phosphatase , chemistry , enzyme assay , phosphorylation , size exclusion chromatography
A phosphatase was purified through a combination of ion‐exchange and hydrophobic chromatography followed by native PAGE from Physarum plasmodia. Recently, we demonstrated that this phosphatase isoform has a hydrolytic activity towards the PMLC (phosphorylated light chain of Physarum myosin II) at pH 7.6. The apparent molecular mass of the purified enzyme was estimated at approximately 50 kDa by means of analytical gel filtration. The enzyme was purified 340‐fold to a final phosphatase activity of 400 pkat/mg of protein. Among the phosphorylated compounds tested for hydrolytic activity at pH 7.6, the enzyme showed no activity towards nucleotides. At pH 7.6, hydrolytic activity of the enzyme against PMLC was detected; at pH 5.0, however, no hydrolytic activity towards PMLC was observed. The K m of the enzyme for PMLC was 10 μM, and the V max was 1.17 nkat/mg of protein. Ca 2+ (10 μM) inhibited the activity of the enzyme, and Mg 2+ (8.5 μM) activated the dephosphorylation of PMLC. Mn 2+ (1.6 μM) highly stimulated the enzyme's activity. Based on these results, we concluded that the enzyme is likely to be a phosphatase with hydrolytic activity towards PMLC.