Sc. Tso et Yr. Chen, ISOLATION AND CHARACTERIZATION OF A GROUP-III ISOZYME OF ACID-PHOSPHATASE FROM RICE PLANTS, Zhongyang yanjiuyuan. zhiwuxue huikan, 38(4), 1997, pp. 245-250
The acid phosphatases (EC 3. 1. 3. 2.) of rice seedlings consisted of
four groups of isozymes. The group III isozyme was purified through am
monium sulfate, DEAE-Sepharose, Con A-Sepharose, and chromatofocusing.
A 198-fold enhancement of activity was attained. This isozyme showed
only one band in native-polyacryamide gel electrophoresis. However, ge
l filtration revealed two peaks of enzyme activity. Their molecular we
ights were 130 kDa and 100 kDa. The purified isozyme showed a pH optim
um of 5. Its Km for p-nitrophenyl phosphate (p-NPP) hydrolysis was 0.3
3 mM. Its activity was inhibited non-competitively by sodium fluoride.
Mercuric chloride, sodium molybdate, and copper sulfate strongly inhi
bited the enzyme activity. The isozyme actively hydrolyzed adenosine t
riphosphate and p-NPP, and partially utilized fructose-1,6-diphosphate
. It did not utilize fructose-6-phosphate, glucose-1-phosphate, glucos
e-6-phosphate, glycerophosphate, or adenosine monophosphate.