THERMODYNAMIC AND KINETIC STUDIES OF PROTEIN STRUCTURE AND ENZYME MECHANISMS

这个实验室从事蛋白质结构和蛋白质的研究。 一种蛋白质分子被合成为一种 随机卷曲，可以折叠成特定的二级和三级结构， 没有任何外部帮助。研究的主要对象是猪。 胃蛋白酶原，是一种相对分子质量为39,630的单体蛋白质， 在pH值在6到8.5之间稳定。在pH 6以下，胃蛋白酶原自我激活 通过蛋白质分解损失其最初的44个氨基酸，产生一个 具有酶活性的蛋白质，胃酶。胃酶只有在pH低于以下时才稳定 6.这两种蛋白质在高pH、高温度或高温度下都能展开 变性剂的浓度，如尿素。在这样的展开之后， 当返回天然状态时，胃蛋白酶原可以重新折叠到其正常结构 条件，而胃酶不能。利益是这个机制中的一个因素 复性反应及序列改变对蛋白质的影响 这两种蛋白质的行为。使用技术，例如 紫外光、圆二色和荧光光谱仪 通过化学修饰和肽化学，该化合物的结构 描述了本地物种和未展开物种的特征。使用RAPID 运动技术，如停流和T-跳跃，中间， 在折叠反应中检测到部分折叠的形式，它们的 结构已部分确定，并且 将它们与天然生物分离并展开的化学反应 已调查的表格。

This laboratory is engaged in studies on protein structure and the mechanism by which a protein molecule, which is synthesized as a random coil, can fold into a specific secondary and tertiary structure, without any external help. The main subject of research is swine pepsinogen, a monomeric protein of molecular weight= 39,630, which is stable at pH's between 6 and 8.5. Below pH 6 pepsinogen activates itself by proteolytic loss of its first 44 amino acids, to produce an enzymatically active protein, pepsin. Pepsin is stable only at pH's below 6. Both proteins are unfolded by exposure to high pH, temperature or concentrations of denaturants, such as urea. After such unfolding, pepsinogen can refold to its normal structure, when returned to native conditions, whereas pepsin cannot. Interest is in the mechanism of this refolding reaction and on the influence of the change in sequence on the behaviour of the two proteins. Using techniques such as ultra-violet, circular dichroic and fluorescence spectroscopies, together with chemical modification and peptide chemistry, the structures of the native and unfolded species have been characterized. Using rapid kinetic techniques, such as stopped-flow and T-jump, intermediate, partly folded forms have been detected in the folding reaction , their structures have been partially determined and the nature of the chemical reactions which separate them from the native and unfolded forms investigated.