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Plant Physiology 76:40-44 (1984) © 1984 American Society of Plant Biologists Further Studies on myo-Inositol-1-phosphatase from the Pollen of Lilium longiflorum Thunb 1Program in Biochemistry/Biophysics and the Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340
myo-Inositol-1-phosphatase has been purified to homogeneity from Lilium longiflorum pollen using an alternative procedure which includes pH change and phenyl Sepharose column chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis shows that the enzyme is a dimer (subunit molecular weight, 29,000 daltons). The enzyme is stable at low pH values and is inactivated only below pH 3.0. In addition to 1L-and 1D-myo-inositol-1-phosphate, it shows high specificity for 1L-chiro-inositol-3-phosphate. As observed earlier with other primary phosphate esters, D-glucitol-6-phosphate and D-mannitol-6-phosphate are hydrolyzed very slowly. No activity is observed with inorganic pyrophosphate or myo-inositol pentaphosphate as substrate. The enzyme is inhibited by fluoride, sulfate, molybdate, and thiol-directed reagents. Partial protection against N-ethylmaleimide inhibition by substrate and Mg2+ together suggests sulfhydryl involvement at the active site.
1 Supported in part by Grant GM-22427 from the National Institute of Health, United States Public Health Service. Scientific Paper No. 6763, Project 0266, College of Agriculture Research Center, Washington State University, Pullman, WA 99164. This article has been cited by other articles:
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