• Journal of Life Science
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• v.21 no.1
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• pp.31-35
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• 2011

Dual-specificity protein phosphatases (DUSPs) constitute a family of protein phosphatase characterized by the ability to dephosphorylate phospho-tyrosyl and phospho-seryl/threonyl residues. Most DUSPs are involved in regulation of cell survival and differentiation. In this study, a human dual-specificity protein phosphatase, DUSP28, was isolated from a human kidney cDNA. The recombinant protein was successfully produed in E.coli and showed sufficient phosphatase activity toward DiFMUP (6,8-difluoro-4-methylumbelliferyl phosphate). Various phosphatase inhibitors and divalent metals were tested for their effects on the DUSP28 phosphatase activity. As a result, $Zn^{2+}$ was found to strongly inhibit DUSP28 phosphatase activity, suggesting DUSP28 is involved in Zn-related signal transduction pathway. Furthermore, the DUSP28 protein preferred phospho-tyrosyl residues to phospho-threonyl residues, implying its physiological roles in the cellular process.

• Environmental Engineering Research
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• v.13 no.4
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• pp.165-168
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• 2008

Measurements of phosphatase activity in peatlands are made difficult by the low levels of activity and the characteristically high concentrations of dissolved organic matter within the sediments. These materials may cause high background absorbances in colorimetric assays, and quenching interference in fluorimetric assays. This review describes the development of a new approach which allows such problems to be overcome by using HPLC to separate the interferences from the products of enzymic hydrolysis. This approach is applicable to various environmental samples such as peat, wetland sediment, and sludge which may contain a large amount of interfering organic matters.