Briley P A, Eisenthal R, Harrison R, Smith G D
Biochem J. 1977 Oct 1;167(1):193-200. doi: 10.1042/bj1670193.
Addition of difluoro-oxaloacetate to the aminic form of aspartate transaminase causes a rapid shift of absorbance maximum of the enzyme from 332 nm to 328 nm, followed by a much slower shift to 360 nm corresponding to complete conversion of the aminic form of the enzyme into the aldimine form or a species with similar spectral parameters in rapid equilibrium with it. Kinetic analysis of both the initial fast reaction and the overall slow reaction by using repeated spectral scanning and stopped-flow techniques allows formulation of a basic reaction mechanism involving at least two intermediate enzyme complexes. Computer simulation of the progress curves of the initial fast reaction based on the suggested reaction mechanism gives kinetic parameters that are consistent with all the data obtained by other methods. A molecular reaction scheme involving a ketimine Schiff-base intermediate is proposed.
向天冬氨酸转氨酶的氨基形式中添加二氟草酰乙酸会导致该酶的最大吸光度迅速从332 nm 移至328 nm，随后是一个慢得多的移至360 nm 的过程，这对应于该酶的氨基形式完全转化为醛亚胺形式或与它处于快速平衡的具有相似光谱参数的物种。通过使用重复光谱扫描和停流技术对初始快速反应和整体缓慢反应进行动力学分析，能够构建一个涉及至少两种中间酶复合物的基本反应机制。基于所提出的反应机制对初始快速反应的进程曲线进行计算机模拟，得到的动力学参数与通过其他方法获得的所有数据一致。提出了一个涉及酮亚胺席夫碱中间体的分子反应方案。
