猪肩胛骨软骨无机焦磷酸酶的特性
Properties of inorganic pyrophosphatase of pig scapula cartilage.
作者信息
Felix R, Fleisch H
出版信息
Biochem J. 1975 Apr;147(1):111-8. doi: 10.1042/bj1470111.
The properties of a highly purified inorganic pyrophosphatase (pyrophosphate phosphohydrolase; EC 3.6.1.1) from pig scapula cartilage were studied. The enzyme had a molecular weight of 66 000 and a pH optimum of 7-8. It was markedly activated by magnesium, but not, or only to a much smaller degree, by other metal ions. PP1 was the only substrate found and had a Km value of 11 muM. The enzyme was not inhibited by phosphate and other inhibitors of alkaline phosphatase such as CN- minus, amino acids and theophylline; it was slightly inhibited by tartrate, formaldehyde and ammonium molybdate and strongly inhibited by F- minus, Ca2+ and other metal ions. The properties of the enzyme in the presence of concentrations of PP1 present in plasma (3.5 muM) were similar to those found at higher (2 mM) concentrations of PP1. The diphosphonates ethane-1-hydroxy-1,1-diphosphonate and dichloromethylenediphosphonate inhibited the enzyme in the presence of low PP1 concentrations. The characteristics of this enzyme are therefore similar to pyrophosphatases from other sources, such as from yeast and erythrocytes, and do not support a specific role of this enzyme in the calcification process.
对从猪肩胛骨软骨中提取的高纯度无机焦磷酸酶（焦磷酸磷酸水解酶；EC 3.6.1.1）的性质进行了研究。该酶的分子量为66000，最适pH值为7 - 8。它被镁显著激活，但不被其他金属离子激活，或仅在很小程度上被激活。PP1是唯一发现的底物，其Km值为11μM。该酶不受磷酸盐和碱性磷酸酶的其他抑制剂（如CN⁻、氨基酸和茶碱）的抑制；它被酒石酸盐、甲醛和钼酸铵轻微抑制，被F⁻、Ca²⁺和其他金属离子强烈抑制。在血浆中存在的PP1浓度（3.5μM）下该酶的性质与在较高（2 mM）浓度的PP1下发现的性质相似。二膦酸盐乙烷 - 1 - 羟基 - 1,1 - 二膦酸盐和二氯亚甲基二膦酸盐在低PP1浓度下抑制该酶。因此，这种酶的特性与来自其他来源（如酵母和红细胞）的焦磷酸酶相似，不支持该酶在钙化过程中具有特定作用。
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