Isolation and Characterization of Phosphatase Enzyme from the Freshwater Macroalga Cladophora glomerata Kützing (Chlorophyta)
2006
A.M. El-Shahed | H. Ibrahim | M. Abd-Elnaeim
Acid phosphatase enzyme (acPase) has been isolated from Cladophora glomerata Kützing and its kinetic properties were investigated. The optimum pH for activity of both the two isolated fractions; the cell wall-bound and the secreted acPases was found to be 4.5. Both fractions exhibited another peak of activity at 9.5 which was attributed to an alkaline phosphatase. The optimum protein concentration that resulted in maximal enzyme activities for both fractions was 8 mg mL<SUP>-1</SUP>. The Km value determined with p-nitrophenyl phosphate (pNPP) was 24 and 14 mM for the cell wall-bound and the secreted acPases, respectively. The enzyme was inhibited by phosphate in the form of KH<SUB>2</SUB>PO<SUB>4</SUB>, molybdate in the form of K<SUB>2</SUB>MoO<SUB>4</SUB>, zinc in the form of ZnCl<SUB>2</SUB>.4H<SUB>2</SUB>O and iodine as KI. Zinc ions were the most potent inhibitor among all the tested inhibitors (max. % inhibition was 96 and 80% for the cell wall- bound and the secreted acPases, respectively). Molybdate had the least inhibitory effects (72 and 50%) on the cell wall- bound and the secreted acPases respectively at 40 mM concentration.
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