Activation and inhibition of the brush-border membrane-bound alkaline phosphatase activity of Hymenolepis diminuta (Cestoda) by divalent cations.
In the absence of exogenous divalent cations, the isolated brush-border plasma membrane of Hymenolepsis diminuta possesses alkaline phosphatase activity (APA). APA is stimulated in the presence of exogenous Mg2+ and inhibited by low concentrations of Zn2+ or high concentrations of Ca2+, and inhibition of APA by Zn2+ is reversed by both Mg2+ and Ca2+. APA is inhibited by ethylenediamine tetraacetic acid (EDTA), ethyleneglycol-bis-(beta-aminoethyl ether) N,N'-tetraacetic acid, and 1,10-phenanthroline in time- and concentration-dependent fashions, with EDTA being the most effective inhibitor. Following treatment with EDTA, APA is restored by Mg2+ and, to a lesser extent, by Ca2+, but not by Zn2+. Thus, APA represents a Mg2(+)-dependent enzyme that can be partly activated by Ca2+ but only in the absence of Mg2+.
Pappas
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Department of Zoology, Ohio State University, Columbus 43210.
D000469:Alkaline Phosphatase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D006926:Hymenolepis / Q000201:enzymology*; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D008871:Microvilli / Q000201:enzymology; D010618:Phenanthrolines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D015032:Zinc / Q000494:pharmacology
D008565:Membrane Proteins; D010618:Phenanthrolines; D004533:Egtazic Acid; D004492:Edetic Acid; D000469:Alkaline Phosphatase; D008274:Magnesium; D015032:Zinc; D002118:Calcium; C025205:1,10-phenanthroline