Competitive, uncompetitive, and mixed inhibitors of the alkaline phosphatase activity associated with the isolated brush border membrane of the tapeworm Hymenolepis diminuta

✍ Scribed by Peter W. Pappas; David A. Leiby

• Publisher: John Wiley and Sons
• Year: 1989
• Tongue: English
• Weight: 528 KB
• Volume: 40
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/jcb.240400212

✦ Synopsis

Several compounds were tested as inhibitors of the alkaline phosphatase (AlkPase) activity associated with the isolated brush border membrane of the tapeworm, Hymenolepis diminuta. Molybdate, arsenate, arsenite and P-glycerophosphate (BGP) were competitive inhibitors of the hydrolysis of pnitrophenyl phosphate, while levamisole and clorsulon were uncompetitive and mixed inhibitors, respectively. Molybdate was also a competitive inhibitor of the hydrolysis of BGP and 5'adenosine monophosphate, and levamisole was an uncompetitive inhibitor of BGP hydrolysis. The apparent inhibitor constants (K;) for molybdate and levamisole were virtually identical regardless of the substrate, and these data support the hypothesis that the AlkPase activity is represented by a single membranebound enzyme with low substrate specificity. Quinacrine, Hg +, and ethylenediaminetetraacetate were also potent inhibitors of the AlkPase activity, but the mechanisms by which these latter three inhibitors function were not clear.