D -3,4-二羟基丁酸 ( D -3,4-DHBA) 是一种重要的平台化学品,在化学和制药行业具有多种应用。报道的从D -木糖产生D -3,4 -DHBA的代谢途径涉及两个 NAD 依赖性脱氢酶催化反应,因此是氧化还原不平衡的。在这项研究中,来自天蓝色链霉菌A3 (ScAldO) 的突变型糖醇氧化酶被鉴定为催化D -木糖和D -3,4-二羟基丁醛的氧化,这是D -3,4所需的两种 NAD 依赖性脱氢酶催化反应-DHBA生产。然后,体外构建了由ScAldO、来自Paralcaligenes ureilyticus的二羟基酸脱水酶、来自乳酸乳球菌的α-酮酸脱羧酶和来自黑曲霉的过氧化氢酶组成的酶级联,用于从D-木糖生产D -3,4 - DHBA。在最佳条件下,由D-木糖生产出浓度为4.55 g L -1的D -3,4- DHBA,摩尔收率为83%,产率为0.217 g L -1 h -1。体外
Deoxygenated and alkylated furanoses: Thorpe—Ingold effects on tautomeric equilibria and rates of anomerization
作者:Joseph R. Snyder、Anthony S. Serianni
DOI:10.1016/0008-6215(91)80110-9
日期:1991.3
to significantly affect both the thermodynamics and kinetics of furanoseanomerization. Increased substitution enhances the proportion of cyclic forms in solution by stimulating furanose kclose. In contrast, furanose kopen was less affected by the degree of substitution; however, kinetic studies of 2-deoxyfuranose anomerization implicate furanose ring conformation as a potential determinant of kopen
An aldose having n-1 carbon atoms is produced from an aldonic acid having n carbon atoms using hypochlorous acid or a hypochlorite in a high yield at low cost with safety, by treating the reaction mixture with a compound having reactivity with the hypochlorous acid or hypochlorite higher than that with the produced aldose.
Syntheses of l-threose and d-erythrose analogues modified at position 2
作者:Corinne André、Jean Bolte、Colette Demuynck
DOI:10.1016/s0957-4166(98)00126-8
日期:1998.4
2-O-Methyl-d-erythrose, 2-O-methyl-l-threose, 2-deoxy-d- and l-erythrose, and the corresponding acetonides have been prepared from the commercially available d-isoascorbic and l-ascorbic acids. The proportion of cyclic (α and β furanoses) and acyclic (aldehyde and hydrate) forms was determined in aqueous (D2O) solution by 1H and 13C NMR spectroscopy.
由可商购的d-异抗坏血酸和l-抗坏血酸制备2-O-甲基-d-赤藓糖,2-O-甲基-1-苏糖,2-脱氧-d-和l-赤藓糖,以及相应的丙酮化物。 。通过1 H和13 C NMR光谱法测定(D 2 O)水溶液中环状(α和β呋喃糖酶)和非环状(醛和水合物)形式的比例。
Photolysis of d-fructose in aqueous solution
作者:Christian Triantaphylides、Heinz-Peter Schuchmann、Clemens von Sonntag
DOI:10.1016/s0008-6215(00)81031-9
日期:——
10 6 s −1 ); ( b ) consecutive elimination of two molecules of water from the tetritol radicals; and ( c ) disproportionation and combination reactions. A peculiar products is trans -4-hydroxy-2-butenal, whose precursor is formedfrom the tetritol radical through elimination of two molecules of water. This compound is a good radical-scavenger and during photolysis quickly attains a low steady-state
摘要在d-果糖水溶液的254 nm光解中,只有与环状形式平衡存在的〜0.8%程度的开链形式吸收光。对产物及其量子产率的研究表明,主要的主要过程是C 4键裂解α到羰基的过程。在没有氧气的情况下,所得自由基的后续反应是:(a)羟烷基酰基自由基中的CO损失(估计速率常数a〜3×10 6 s -1);(b)从四糖醇自由基中连续消除两个分子的水;(c)歧化反应和组合反应。一种特殊的产物是反式-4-羟基-2-丁烯醛,其前体是通过消除两个分子的水而由四糖醇自由基形成的。该化合物是一种良好的自由基清除剂,在光解过程中很快达到较低的稳态浓度。衍生自它的产物之一是2,3-二脱氧-2,3-二-C-羟甲基四糖。在氧的存在下,CO的消除过程是部分的,并且通过将氧快速添加到酰基烷基和羟烷基自由基来完全抑制水的消除反应。过氧自由基通过从α-羟烷基过氧自由基中单分子消除HO 2和双分子歧化反应而失去O 2进行反应,当涉及到羟烷基酰基过氧自由基时,CO
520. The action of base on methanesulphonyl esters of reducing sugars