stereoselective and produced branched‐chain monosaccharide adducts with a tertiary alcohol moiety. Several aldols were readily obtained in good to excellent yields (from 76 to 95 %). These results contradict the general view that aldehydes are the only electrophile substrates for DHAP‐dependent aldolases and provide a new C−C bond‐forming enzyme for stereoselective synthesis of tertiary alcohols.
Towards a Mechanistic Understanding of Factors Controlling the Stereoselectivity of Transketolase
作者:Anna Baierl、Axel Theorell、Ursula Mackfeld、Philipp Marquardt、Friederike Hoffmann、Stephanie Moers、Katharina Nöh、Patrick C. F. Buchholz、Jürgen Pleiss、Martina Pohl
DOI:10.1002/cctc.201800299
日期:2018.6.21
relevant amino acids of TKs from different species, a standard numbering scheme was developed. Using this concept, H26, H261, and F434 were identified as the key residues which mediate stereoselectivity, where two main factors influenced the arrangement of ThDP‐bound donor and acceptor prior to carboligation: the relative orientation of the substrate side chains and the orientation of the acceptor carbonyl
Biochemical properties and phylogeny of hydroxypyruvate reductases from methanotrophic bacteria with different c1-assimilation pathways
作者:S. Y. But、S. V. Egorova、V. N. Khmelenina、Y. A. Trotsenko
DOI:10.1134/s0006297917110074
日期:2017.11
methanotrophic Hpr confirmed a key role of the enzyme in utilization of C1-compounds via the serine cycle. The enzyme from Ms. trichosporium OB3b realizing the serine cycle as a sole assimilation pathway had much higher special activity and affinity in comparison to Hpr from Mm. alcaliphilum 20Z and Mc. capsulatus Bath assimilating carbon predominantly via the ribulose monophosphate (RuMP) cycle. The hpr gene
Synthesis with good enantiomeric excess of both enantiomers of α-ketols and acetolactates by two thiamin diphosphate-dependent decarboxylases
作者:Ahmet Baykal、Sumit Chakraborty、Afua Dodoo、Frank Jordan
DOI:10.1016/j.bioorg.2006.09.006
日期:2006.12
stereoselectivity for forming the carboligase products acetoin, acetolactate, and phenylacetylcarbinol by the E477Q and D28A YPDC, and the E636A and E636Q PDHc-E1 active-center variants. Both pyruvate and beta-hydroxypyruvate were used as substrates and the enantiomeric excess was analyzed by a combination of NMR, circular dichroism and chiral-column gas chromatographic methods. Remarkably, the two enzymes produced
除2-氧代酸的脱羧作用外,依赖于硫胺素二磷酸酯(ThDP)的脱羧酶/脱氢酶还可以进行所谓的羰基化反应,其中与ThDP结合的中央烯胺中间体与亲电底物发生反应。例如,酵母丙酮酸丙酮酸脱羧酶(YPDC,来自酿酒酵母)或大肠杆菌丙酮酸丙酮酸脱氢酶复合物的E1亚基(PDHc-E1)可产生乙酰丁酸和乙酰乳酸,这是由于与硫胺素二磷酸结合的中央烯胺与分别为乙醛和丙酮酸。早些时候,我们已经表明,一些活跃的中心变体确实比通常的变体更喜欢这样的一个碳连接酶途径[Sergienko,Jordan,Biochemistry 40(2001)7369-7381; Sergienko,Jordan,Biochemistry 40(2001)7369-7381; Sergienko,Jordan,Biochemistry 40(2001)7369-7381。Nemeria et al。,J.Biol.Chem。,1987。化学
Influence of Transketolase-Catalyzed Reactions on the Formation of Glycolaldehyde and Glyoxal Specific Posttranslational Modifications under Physiological Conditions
作者:Alexander Klaus、Tim Baldensperger、Roman Fiedler、Matthias Girndt、Marcus A. Glomb
DOI:10.1021/acs.jafc.7b05472
日期:2018.2.14
of 13C-labeled compounds. For the first time, glycolaldehyde and other sugars involved in the TK reaction were quantified in vivo and compared to nondiabetic uremic patients undergoing hemodialysis. Quantitation revealed amounts of glycolaldehyde up to 2 μM and highlighted its crucial role in the formation of AGEs in vivo. In this context, a LC–MS2 method for the comprehensive detection of sedoheptulose-7-phosphate