Lee J, Coward J K
Interdepartmental Program in Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor 48109.
Biochemistry. 1993 Jul 6;32(26):6794-801. doi: 10.1021/bi00077a034.
Chemically synthesized peptide and lipid disaccharide substrates have been used to investigate two possible mechanisms for enzyme-catalyzed N-glycosylation. Using microsomal oligosaccharyltransferase isolated from yeast, the fate of the deuterium in three stereospecifically deuterated peptides has been investigated. In all three cases, the deuterium present in the peptide substrate was retained in the glycopeptide product, as shown clearly by 1H NMR spectral comparisons. The lack of deuterium wash-out during catalysis provides strong evidence against either enol lactone or ketene formation as an intermediate in this reaction.
化学合成的肽和脂质二糖底物已被用于研究酶催化N-糖基化的两种可能机制。利用从酵母中分离出的微粒体寡糖基转移酶，研究了三种立体定向氘代肽中氘的去向。在所有三种情况下，肽底物中存在的氘保留在糖肽产物中，1H NMR光谱比较清楚地表明了这一点。催化过程中氘的缺乏为该反应中烯醇内酯或乙烯酮形成作为中间体提供了有力的反证。
