Majeska R J, Wuthier R E
Biochim Biophys Acta. 1975 May 23;391(1):51-60. doi: 10.1016/0005-2744(75)90151-5.
Fractions composed primarily of cells (Fraction I), membrane fragments (Fraction II) and matrix vesicles (Fraction III) were isolated from chick epiphyseal cartilage. The characteristics of the alkaline phosphatase (EC 3.1.3.1), pyrophosphatase (EC 3.6.1.1) and ATPase (EC 3.6.1.3) activities in the matrix vesicle fraction were studied in detail. Mg-2-+ was not absolutely essential to any of the activities, but at low levels was stimulatory in all cases. Higher concentrations inhibited both pyrophosphatase and ATPase activities. Both the stimulatory and inhibitory effects were pH-dependent. Ca-2-+ stimulated all activities weakly in the absence of Mg-2-+. However, when Mg-2-+ was present, Ca-2-+ was slightly inhibitory. Thus, none of the activities appear to have a requirement for Ca-2-+, and hence would not seem to be involved with active Ca-2-+ transport in the typical manner. The distribution of alkaline phosphatase, pyrophosphatase, and Mg-2-+ ATPase activities among the various cartilage fractions was identical, and concentrated primarily in the matrix vesicles. Conversely, the highest level of (Na-+ + K-+)-ATPase activity was found in the cell fraction. All activites showed nearly identical sensitivities to levamisole (4 - 10-3 M) which caused nearly complete inhibition of alkaline phosphatase and pyrophosphatase. About 10-15% of the ATPase activity was levamisole-insensitive. The data are consistent with the concept that the Mg-2-+-ATPase and pyrophosphatase activities of matrix vesicles stem from one enzyme, namely, alkaline phosphatase.
从鸡骨骺软骨中分离出主要由细胞组成的部分（部分I）、膜碎片（部分II）和基质小泡（部分III）。详细研究了基质小泡部分中碱性磷酸酶（EC 3.1.3.1）、焦磷酸酶（EC 3.6.1.1）和ATP酶（EC 3.6.1.3）活性的特征。Mg²⁺对任何一种活性都不是绝对必需的，但在低水平时在所有情况下都具有刺激作用。较高浓度会抑制焦磷酸酶和ATP酶的活性。刺激和抑制作用均依赖于pH值。在没有Mg²⁺的情况下，Ca²⁺对所有活性的刺激作用较弱。然而，当存在Mg²⁺时，Ca²⁺会有轻微抑制作用。因此，似乎没有一种活性需要Ca²⁺，因此似乎不会以典型方式参与主动Ca²⁺转运。碱性磷酸酶、焦磷酸酶和Mg²⁺-ATP酶活性在各种软骨部分中的分布是相同的，并且主要集中在基质小泡中。相反，在细胞部分中发现（Na⁺+K⁺）-ATP酶活性的最高水平。所有活性对左旋咪唑（4×10⁻³ M）表现出几乎相同的敏感性，左旋咪唑会导致碱性磷酸酶和焦磷酸酶几乎完全抑制。约10%-15%的ATP酶活性对左旋咪唑不敏感。这些数据与基质小泡的Mg²⁺-ATP酶和焦磷酸酶活性源自一种酶即碱性磷酸酶的概念一致。
