Selective oxidation of primary alcohols mediated by nitroxyl radical in aqueous solution. Kinetics and mechanism
作者:Arjan E.J. de Nooy、Arie C. Besemer、Herman van Bekkum
DOI:10.1016/0040-4020(95)00417-7
日期:1995.7
The kinetics of the TEMPO-mediated oxidation of methyl α-d-glucopyranoside to sodium methyl α-d-glucopyranosiduronate were studied. An intermediate was found which was identified as the hydrated aldehyde. This was oxidised in the same manner as the alcohol, with pseudo first order rate constants ratio kobs,ald/kobs,alc — 7. The reaction mechanism is discussed with emphasis on steric factors and compared
研究了TEMPO介导的α-d-吡喃葡萄糖苷甲基氧化成α-d-吡喃葡萄糖苷神经酸钠的动力学。发现了一种中间体,该中间体被鉴定为水合醛。以与醇相同的方式将其氧化,具有伪一级速率常数比率k obs,ald / k obs,alc -7。讨论了反应机理,着重于空间因素,并与文献数据进行了比较。假定了两种不同的反应途径。在碱性反应条件下通过环状过渡态3,在酸性反应条件下通过非环状过渡态4。
Method for detecting and counting micro-organisms in a sample
申请人:Vedrine Bruno
公开号:US20050202518A1
公开(公告)日:2005-09-15
The invention concerns a method for detecting and counting micro-organisms in a sample comprising the following steps: (a) selectively enriching the micro-organism sought in the sample, (b) conditioning said micro-organism, (c) immunomagnetic concentration of the conditioned microorganism, (d) fluorescent marking of the concentrated micro-organism, and (e) detecting and analyzing the fluorescence.
Glycosyltransferase catalyzed assemblage of sialyl-Lewisa-saccharopeptides
作者:Gabi Baisch、Reinhold Öhrlein
DOI:10.1016/s0008-6215(98)00229-8
日期:1998.11
A series of methyl hexopyranosiduronic acids are coupled to type I disaccharide amines to give 'trisaccharides' which have the natural N-acetyl group of the type I disaccharides replaced by uronic acids (--> saccharopeptides). These saccharopeptides are surprisingly good substrates for alpha-2,3-sialyltransferase and fucosyltransferase III. The enzymes transfer N-acetylneuraminic acid and fucose, respectively, onto these acceptor substrates, despite the far reaching alterations, regio- and stereospecifically in the expected manner to yield sialyl-Lewis(a)-saccharopeptides. (C) 1998 Elsevier Science Ltd. All rights reserved.
Glycosyl-transferase catalyzed assemblage of sialyl-lewis x -saccharopeptides
作者:Gabi Baisch、Reinhold Öhrlein
DOI:10.1016/s0968-0896(98)00107-2
日期:1998.10
A series of glycohexopyranuronic acids are coupled to glucosamines to give 'disaccharides' which have the natural N-acetyl group of the glcNAc-moiety replaced by various sugar acids (-->saccharopeptides). These saccharopeptides are surprisingly good substrates for beta(1-4)galactosyl-transferase, alpha(2-3)sialyl-transferase, and fucosyl-transferase VI. The enzymes transfer successively galactose, sialic acid, and fucose from the corresponding donors onto these acceptor substrates-despite the far reaching alterations-regio- and stereospecifically in the expected manner to yield a new class of compounds, the sialyl-Lewis(x)-saccharopeptides. (C) 1998 Elsevier Science Ltd. All rights reserved.