PROTEINASE INHIBITORS & CRYSTALLIN FRAGMENTS IN CATARACT

描述：蛋白质的修饰在改变一种 将正常晶状体变成白内障晶状体。多肽键的蛋白水解性断裂 内源性酶在晶体蛋白中的作用可能是最常见的 以及重要的修改。到目前为止，关于这些卵裂的信息在 晶体蛋白在其酶性质方面是有限的，在 酶和底物水平对晶体蛋白功能的影响 晶体蛋白片段的修饰。 根据初步结果，私家侦探推测生物降解 在酶和底物水平上都受到调节，并且 被切割的片段经过二次修饰，如通过 美拉德反应，并因此直接参与交联剂 晶状体蛋白质是晶状体混浊形成的中心。至 检验这一假设，将追求以下三个具体目标： (1)具体目标#1：确定自溶激活的机制 一种可能的酶原型激活的膜蛋白水解酶 Ba3/A1-晶体蛋白水解酶由去污剂，如脱氧胆酸钠。 (2)特定目标#2：确定膜蛋白水解酶和 BA3/A1-晶状体蛋白水解酶在体内的蛋白水解性 晶体蛋白。(3)具体目标3：确定降解产物的交联度 9 kDa YD-晶体蛋白片段的一般多肽和特异性多肽 形成同源(单独的晶体蛋白片段)和异源(晶体蛋白 片段和天然晶体蛋白)多聚体可能通过糖基化 美拉德反应的机理。 上述研究将解决有关体内的问题 晶状体蛋白降解的调控及内源性蛋白酶的作用 在这个过程中。这项研究还将回答以下问题： 降解的多肽在二次修饰后获得交联性 性质并直接参与蛋白质的交联化 晶状体混浊的发展。因为所有拟议的研究都将是 在人类的晶状体中进行，结果将直接与 人类老年性白内障问题。

DESCRIPTION: Modification of proteins play a pivotal role in changing a normal lens into a cataractous lens. Proteolytic cleavage of peptide bonds in crystallins by endogenous enzymes is probably one of the most frequent and important modifications. So far, information about these cleavages in crystallins is limited in terms of their enzymatic nature, regulation at the enzyme and substrate levels, effect on crystallin functions and secondary modifications in crystallin fragments. Based on preliminary results, the P.I. has hypothesized that the degradation of crystallins is regulated at both enzyme and substrate levels and the cleaved fragments undergo secondary modification such as glycation via the Maillard reaction and therefore directly participate in the cross-linking of the lens proteins which is central to the development of lens opacity. To test this hypothesis, the following three specific aims will be pursued: (1) specific Aim #1: Determine the mechanism of autolytic activation of a membrane proteinase from a putative zymogen type activation of the BA3/A1-crystallin proteinase by a detergent such as sodium deoxycholate. (2) specific Aim #2: Determine the role of the membrane proteinase and BA3/A1-crystallin proteinase in the in vivo proteolysis of selected crystallins. (3) Specific Aim #3: Determine crosslinking of degraded polypeptides in general and specifically of a 9 kDa yD-crystallin fragment to form homologous (crystallin fragments alone) and heterologous (crystallin fragments plus native crystallins) multimers possibly via the glycation mechanism of the Maillard reaction. The above studies will address the questions regarding the in vivo regulation of crystallin degradation and the role of endogenous proteinases in this process. This study will also answer the questions whether the degraded polypeptides, on secondary modifications, acquire cross-linking properties and participate directly in protein cross-linking during the development of lens opacity. Since all of the proposed studies will be carried out in human lenses, the results will be directly relevant to the human senile cataract problem.