Sauer G R, Wu L N, Iijima M, Wuthier R E
Department of Chemistry and Biochemistry, University of South Carolina, Columbia 29208, USA.
J Inorg Biochem. 1997 Jan;65(1):57-65. doi: 10.1016/s0162-0134(96)00080-3.
The effects of two inhibitors, fluoride (F-) and zinc (Zn2+), were studied on the formation of mineral by matrix vesicles (MV) in an in vitro system. Kinetically, mineral formation by MV incubated in a synthetic cartilage lymph (SCL) is characterized by three phases: a lag period, a period of rapid uptake, and finally a period of slow uptake. Zn2+ at > or = 5 microM completely inhibited MV mineralization; at < or = 1 microM, it had little effect on rate of ion uptake, but delayed conversion of an OCP-like intermediate into hydroxyapatite (OHAp). F- at > or = 10 microM reduced the rate of rapid uptake by MV and caused the OCP-like precursor to convert to OHAp. When synthetic OCP was seeded into SCL, mineralization ensued and OHAp became the dominant phase. With Zn2+ present, OCP-like features persisted longer; with F-, the OCP-like features were lost more rapidly. When ACP was seeded into SCL, OHAp formed; Zn2+ at < or = 1 microM caused OCP-like mineral to form. Our findings indicate that Zn2+ stabilizes a noncrystalline precursor in MV regulating the length of the lag period; Zn2+ also favors the formation of an OCP-like intermediate whose growth accounts for the rapid uptake phase. This OCP-like phase appears to nucleate formation of OHAp by MV.
在体外系统中，研究了两种抑制剂氟化物（F-）和锌（Zn2+）对基质小泡（MV）矿化形成的影响。从动力学角度来看，在合成软骨淋巴液（SCL）中孵育的MV的矿化形成具有三个阶段：延迟期、快速摄取期，最后是缓慢摄取期。浓度大于或等于5 microM的Zn2+完全抑制MV矿化；浓度小于或等于1 microM时，它对离子摄取速率影响很小，但会延迟类OCP中间体向羟基磷灰石（OHAp）的转化。浓度大于或等于10 microM的F-降低了MV的快速摄取速率，并导致类OCP前体转化为OHAp。当将合成OCP接种到SCL中时，矿化随之发生，且OHAp成为主要相。存在Zn2+时，类OCP特征持续时间更长；存在F-时，类OCP特征消失得更快。当将无定形磷酸钙（ACP）接种到SCL中时，形成了OHAp；浓度小于或等于1 microM的Zn2+导致形成类OCP矿物质。我们的研究结果表明，Zn2+稳定了MV中的非晶态前体，调节延迟期的长度；Zn2+还有利于形成类OCP中间体，其生长构成了快速摄取阶段。这种类OCP相似乎通过MV成核形成OHAp。
