The effect of a proteinase trapping agent, alpha-2-macroglobulin, on the activity of immuno- and neural cells

α-2-巨球蛋白是一种多种多样的蛋白水解酶抑制剂，它通过一种称为TRAP机制的独特机制来抑制多种内切酶的活性。该机制假设α-2-M的“诱饵区域”中的多肽键的断裂触发了一个顺序的分子内反应，最终导致捕获该酶的α-2-M的结构发生整体变化。确定诱饵区域的水解率和后续反应的速率，包括结构变化，一直是诱捕机理研究的关键问题。在这项研究中，我们首次成功地测定了诱饵区域的裂解率和全球结构改变的比率。作为这项研究的下一项成就，我们检验了我们的假设，即α-2-M可以作为抗原提呈细胞(如巨噬细胞)的多肽疫苗的有效载体。开发多肽疫苗的概念是为了消除来自生物材料的传统疫苗的危险副作用。化学合成的多肽被用来代替传统疫苗，但此类多肽的抗原性较低，应予以加强。我们提出，合成肽可以与α-2-M偶联，并用于宿主动物。这种结合物可以通过受体介导的内吞作用被巨噬细胞有效地摄取，并最终激活高度的抗体产生。本研究对α-2-M对培养神经元的影响进行了研究，结果表明α-2-M具有轴突延伸作用，证实了α-2-M及其受体在脑组织中的存在，表明α-2-M的活性在脑发育过程中具有重要的生理意义。

Alpha-2-macroglobulin is a varsatile protease inhibitor that can inhibits the activity of a large variety of endoproteinases by a unique mechanism called the trap mechanism. The mechanism assumes that the cleavage of peptide bonds in the "bait region" of alpha-2-M triggers off a gequential intra-molecular reactions that finally causes a global change in the structure of alpha-2-M entrapping the proteinase. Determination of the rate of bait region hydrolysis and those of subsequent reactions including the structural change has been a key lsssue in the study of trap mechanism. In this study we have been successful in determining the rate of bait region cleavage and that of the global structural change for the first time.As the next accomplishment in this study, we tested our hypothesis that alpha-2-M can be used as an efficient carrier of peptide vaccines to antigen presenting cells such as macrophages. The peptide vaccine concept has been developed to eliminate the hazardous side effects of conventional vaccines derived from bio-materials. Chemically synthesized peptides are used in place of conventlonal vaccines but the low antigenicity of such peptides should be augmented. WE proposed that synthetic peptides can be conjugated to alpha-2-M and administered to host animals. The conjugate can be efficiently taken up by macrophages via receptor mediated endocytosis and eventually activates a high degree of antibody production. The of such experiment in this study has been very promising.The effect of alpha-2-M the cultured neurons has been examined in this study and the result was positlvely interpreted to show the neurite extension effect of alpha-2-M.The presence of alpha-2-M and its receptor in the brain tissue has been confirmed suggesting the observed activity of the protein could be physiologically important in the brain development.