Abstract
1. The differential effects of adding Zn2+ and Mg2+ on the orthophosphatase and inorganic pyrophosphatase activities of human intestinal alkaline phosphatase were studied. 2. In the presence of excess of Zn2+, inorganic pyrophosphatase activity is inhibited. At higher concentrations of pyrophosphate, hydrolysis of this substrate takes place, but is inhibited competitively by the Zn2+–pyrophosphate complex. This complex also acts as a competitive inhibitor of orthophosphate hydrolysis. 3. Excess of Mg2+ also inhibits pyrophosphatase action by removal of substrate; at low concentrations, this ion activates pyrophosphatase, as is the case with orthophosphatase. 4. It is concluded that, when interactions between metal ions and pyrophosphate are taken into account, the effects of these ions are consistent with the view that alkaline phosphatases possess both orthophosphatase and inorganic pyrophosphatase activities.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- DELSAL J. L., MANHOURI H. Etude comparative des dosages colorimétriques du phosphore. IV. Dosage de l'orthophosphate en présence d'esters phosphoriques; nouvelles méthodes. Bull Soc Chim Biol (Paris) 1958;40(11):1623–1636. [PubMed] [Google Scholar]
- Eaton R. H., Moss D. W. Inhibition of the orthophosphatase and pyrophosphatase activities of human alkaline-phosphatase preparations. Biochem J. 1967 Mar;102(3):917–921. doi: 10.1042/bj1020917. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Eaton R. H., Moss D. W. Kinetic studies on the orthophosphatase and iorganic pyrophosphatase activities of human alkaline phsophatase. Enzymologia. 1968 Sep 30;35(3):168–178. [PubMed] [Google Scholar]
- Eaton R. H., Moss D. W. Organic pyrophosphates as substrates for human alkaline phosphatases. Biochem J. 1967 Dec;105(3):1307–1312. doi: 10.1042/bj1051307. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fernley H. N., Bisaz S. Studies on alkaline phosphatase. Phosphorylation of calf-intestinal alkaline phosphatase by 32P-labelled pyrophosphate. Biochem J. 1968 Mar;107(2):279–283. doi: 10.1042/bj1070279. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fernley H. N., Walker P. G. Studies on alkaline phosphatase. Inhibition by phosphate derivatives and the substrate specificity. Biochem J. 1967 Sep;104(3):1011–1018. doi: 10.1042/bj1041011. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Moss D. W., Eaton R. H., Smith J. K., Whitby L. G. Association of inorganic-pyrophosphatase activity with human alkaline-phosphatase preparations. Biochem J. 1967 Jan;102(1):53–57. doi: 10.1042/bj1020053. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Moss D. W. Influence of metal ions on the orthophosphatase and inorganic pyrophosphatase activities of human alkaline phosphatase. Biochem J. 1969 Feb;111(3):22P–22P. doi: 10.1042/bj1110022pa. [DOI] [PMC free article] [PubMed] [Google Scholar]