Evaluation of the regioselective delactonization of tri-sialic acid lactone by in-solution molecular dynamics simulation

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Title:	Evaluation of the regioselective delactonization of tri-sialic acid lactone by in-solution molecular dynamics simulation
Authors:	Chen, CS (Chen, Chien-Sheng) Yu, YP (Yu, Yi-Ping) Hsu, CH (Hsu, Chun-Hua) Zou, W (Zou, Wei) Fang, JM (Fang, Jim-Min) Wu, SH (Wu, Shih-Hsiung)
Contributors:	Dept Food Hlth & Nutr Sci
Keywords:	Sialic acid Lactone Regioselectivity Reactant complex Molecular dynamics
Date:	2012-06
Issue Date:	2013-02-20 15:47:52 (UTC+8)
Abstract:	An approximate model for the delactonization of tri-sialic acid lactone is presented with two water-layers that led to neutral hydrolysis of delta-lactone. The hydrolytic reactivity was studied with a 10-ns in-solution molecular dynamics simulation. The initial step of this hydrolysis involves a reactant water nucleophile complex via a proton transfer with another water molecule. Therefore, the probability of water molecules localized at the hydrolytic center correlates to the hydrolysis of delta-lactone. The stepwise delactonization of alpha 2,8-(NeuAc)(3) lactone results/resulted from water concentration discrepancy near the carbonyl carbon of lactones in two water oxygen center dot center dot center dot carbonyl carbon shells, and the distances of O=C center dot center dot center dot O-water layers were 2.8 angstrom and 5.1 angstrom. Based on in-solution molecular dynamics study, the motion of water molecules over the re-face of the carbonyl groups was used for the quantitative description of the residence probability, p, whose value is 0.11 for lactone I and 0.33 for lactone II. The geometric criteria used to determine the residence statistics are (1) the distance of water-oxygen center dot center dot center dot carbonyl carbon in less than 5.1 angstrom and (2) the cone angle, theta, of carbonyl O=C center dot center dot center dot O-water in the range of 85-115 degrees. As expected, a higher residence probability at lactone II led to its faster hydrolysis. Both the radial g(r) and angular p(theta) pair distribution functions of water oxygen and carbonyl groups of lactones ensure a better surrounding hydration encounter for lactone II. In contrast, water molecules around lactone I are deduced due to a steric hindrance by the turn structure of alpha 2,8-(NeuAc)(3) lactone. (C) 2012 Elsevier Ltd. All rights reserved.
Relation:	CARBOHYDRATE RESEARCH 卷: 354 頁數: 87-93
Appears in Collections:	[Department of Food and Nutrition ] journal articles

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