Backstrom J R, Miller C A, Tökés Z A
Department of Biochemistry, University of Southern California, Los Angeles.
J Neurochem. 1992 Mar;58(3):983-92. doi: 10.1111/j.1471-4159.1992.tb09352.x.
Three neutral proteinases from human hippocampal tissue have been identified and partially characterized using substrate gel electrophoresis. The proteinases showed activity when gelatin was used as the substrate, but had no detectable activity against casein. Based on the results of inhibition studies and the calcium requirements, it was concluded that the activities were due to calcium-dependent metalloproteinases. The apparent molecular weights were 130,000 (MP-130), 100,000 (MP-100), and 70,000 (MP-70). Half-maximal activities were observed with 20 microM Ca2+ for MP-130, 40 microM Ca2+ for MP-100, and 800 microM Ca2+ for MP-70. In the presence of Ca2+, Zn2+ reestablished the activities of the three metalloproteinases at a lower concentration than did either Co2+ or Mn2+. One millimolar Al3+ inhibited 67% of the MP-70 activity, but did not affect the MP-100 and MP-130 activities. An analysis of Alzheimer-affected hippocampal and control samples showed that the specific activity (in units per milligram of sodium dodecyl sulfate-soluble protein) of MP-70 varied less than the activities of MP-100 and MP-130 between the two groups. Although p-amino-phenylmercuric acetate (p-APMA) increased the activities of MP-70 by 70% in both groups of specimens, the resulting activities from Alzheimer samples were greater than those from control samples (p less than 0.01). A wide range of MP-100 specific activity was observed in both groups, and its mean activity was higher in Alzheimer-affected samples (p less than 0.05). Treatment with p-APMA increased the activity of MP-100 only 25% in both groups of tissue samples. MP-130 activity was detected predominantly in Alzheimer-affected hippocampal specimens, and treatment with p-APMA failed to increase its activity in both the control and the Alzheimer-affected specimens. The results demonstrate an elevated level of metalloproteinase activities, capable of degrading tissue matrix components, in the hippocampus from postmortem Alzheimer patients.
利用底物凝胶电泳已从人海马组织中鉴定出三种中性蛋白酶，并对其进行了部分特性分析。当以明胶作为底物时，这些蛋白酶表现出活性，但对酪蛋白没有可检测到的活性。基于抑制研究结果和对钙的需求，得出结论：这些活性归因于钙依赖性金属蛋白酶。其表观分子量分别为130,000（MP - 130）、100,000（MP - 100）和70,000（MP - 70）。MP - 130在20微摩尔Ca2+时观察到半数最大活性，MP - 100在40微摩尔Ca2+时，MP - 70在800微摩尔Ca2+时观察到半数最大活性。在有Ca2+存在的情况下，Zn2+能以比Co2+或Mn2+更低的浓度恢复这三种金属蛋白酶的活性。1毫摩尔Al3+抑制了67%的MP - 70活性，但不影响MP - 100和MP - 130的活性。对阿尔茨海默病患者的海马组织样本和对照样本进行分析表明，两组之间MP - 70的比活性（以每毫克十二烷基硫酸钠可溶性蛋白的单位数表示）变化小于MP - 100和MP - 130的活性变化。尽管对氨基苯汞乙酸（p - APMA）在两组标本中均使MP - 70的活性增加了70%，但阿尔茨海默病样本产生的活性高于对照样本（p < 0.01）。在两组中均观察到MP - 100的比活性范围很广，且其平均活性在阿尔茨海默病患者受影响的样本中更高（p < 0.05）。在两组组织样本中，用p - APMA处理仅使MP - 100的活性增加了25%。MP - 130的活性主要在阿尔茨海默病患者受影响的海马标本中检测到，用p - APMA处理在对照标本和阿尔茨海默病患者受影响的标本中均未能增加其活性。结果表明，在死后阿尔茨海默病患者的海马中，能够降解组织基质成分的金属蛋白酶活性水平升高。
