As the major and abundant type of glucosinolates(GL)in plants,sinigrin has po-tential functions in promot-ing health and insect defense.The final step in the biosyn-thesis of sinigrin core struc-ture is highly representative in GL compounds,which corre-sponds to the process from 3-methylthiopropyl ds-GL to 3-methylthiopropyl GL catalyzed by sulfotransferase(SOT).However,due to the lack of the crystallographic structure of SOT complexed with the 3-methylthiopropyl GL,little is known about this sulfonation process.Fortunately,the crystal structure of SOT 18 from Arabidop-sis thaliana(AtSOT18)containing the substance(sinigrin)similar to 3-methylthiopropyl GL has been determined.To understand the enzymatic mechanism,we employed molecu-lar dynamics(MD)simulation and quantum mechanics combined with molecular mechanics(QM/MM)methods to study the conversion from ds-sinigrin to sinigrin catalyzed by At-SOT18.The calculated results demonstrate that the reaction occurs through a concerted dissociative mechanism.Moreover,Lys93,Thr96,Thr97,Tyr130,His155,and two enzyme peptide chains(Pro92-Lys93 and Gln95-Thr96-Thr97)play a role in positioning the sub-strates and promoting the catalytic reaction by stabilizing the transition state geometry.Particularly,His155 acts as a catalytic base while Lys93 acts as a catalytic acid in the reac-tion process.The presently proposed concerted dissociative mechanism explains the role of AtSOT18 in sinigrin biosynthesis,and could be instructive for the study of GL biosynthesis catalyzed by other SOTs.

Ya-Jie Guo;Ya-Jun Liu

Key Laboratory of Theoretical and Computational Photochemistry,Ministry of Education,College of Chemistry,Beijing Normal University,Beijing 100875,China;Center for Advanced Materials Research,Advanced Institute of Natural Sciences,Beijing Normal University at Zhuhai,Zhuhai 519087,China

化学物理学报（英文版）

[1]Ya-Jie Guo;Ya-Jun Liu-.QM/MM Study on Enzymatic Mechanism in Sinigrin Biosynthesis)[J].化学物理学报（英文版）,2022(01):193-199

Sinigrin,sponds,methylthiopropyl,Arabidop,AtSOT18,SOT18,Lys93,Thr96,Thr97,Tyr130,His155,Pro92,Gln95,SOTs

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