Minetti G, Balduini C, Brovelli A
Dipartimento di Biochimica, Sezione di Scienze, Università di Pavia.
Ital J Biochem. 1994 Nov-Dec;43(6):273-83.
A new synthetic substrate for protein methionine sulfoxide reductase is proposed. We show that extracts from human polymorphonuclear leukocytes can reduce 4-dimethylaminoazobenzene-4'-sulfonyl-L-methionine-dl-sulfoxide [DABS-L-Met-dl-(O)] to the corresponding methionine derivative, in the presence of dithiothreitol or dithioerythritol. The product of the reaction (DABS-Met) was separated by reversed-phase HPLC and detected by reading the absorbance at 436 nm. Due to the chirality of the sulfur atom in the sulfoxide, two diastereomers of Met(O) exist, namely Met-l-sulfoxide and Met-d-sulfoxide. After separation of the two forms and preparation of the DABS-derivatives, we observed a preferential reduction of the l-sulfoxide by polymorphonuclear leukocytes extracts. We discuss the possibility that the observed stereospecificity might have physiological relevance in the field of the oxidative modifications of proteins.
提出了一种用于蛋白质甲硫氨酸亚砜还原酶的新型合成底物。我们发现，在二硫苏糖醇或二赤藓糖醇存在的情况下，人多形核白细胞提取物可将4-二甲基氨基偶氮苯-4'-磺酰基-L-甲硫氨酸-dl-亚砜[DABS-L-Met-dl-(O)]还原为相应的甲硫氨酸衍生物。通过反相高效液相色谱法分离反应产物（DABS-Met），并通过读取436 nm处的吸光度进行检测。由于亚砜中硫原子的手性，存在两种甲硫氨酸亚砜的非对映异构体，即Met-1-亚砜和Met-d-亚砜。分离这两种形式并制备DABS衍生物后，我们观察到多形核白细胞提取物对1-亚砜有优先还原作用。我们讨论了观察到的立体特异性在蛋白质氧化修饰领域可能具有生理相关性的可能性。
