D-Threonine aldolase is an enzyme belonging to the glycine-dependent aldolases, and it catalyzes the reversible aldol reaction of glycine and acetaldehyde to give D-threonine and/or D-allo-threonine. In this study, a putative D-threonine aldolase gene from Delftia sp. RIT313 was cloned and expressed in Escherichia coli BL21 (DE3). The purified enzyme (DrDTA, 47 KDa) exhibited 21.3 U mg−1 activity for the
d -苏氨醛缩酶是属于甘氨酸依赖性醛缩酶的酶,它催化甘氨酸和乙醛,得到的可逆醛醇缩合反应d -苏氨酸和/或d -异体-苏氨酸。在这项研究中,来自Delftia sp。的一个推定的D-苏氨酸醛缩酶基因。RIT313被克隆并在大肠杆菌BL21(DE3)中表达。纯化的酶(DrDTA,47 KDa)表现出21.3 U mg -1在50°C的MES-NaOH缓冲液(pH 6.0)中添加甘氨酸和乙醛的醛醇缩合酶的活性。反应需要吡ido醛5'-磷酸和金属离子,并且金属离子的存在增强了酶的稳定性。结果发现,转化和C β -stereoselectivity受到显着受反应温度,助溶剂,酶和反应时间的量的影响,并且能够以使动力学控制下进行反应,以保持在合适的转化率和高立体选择性β-碳,从而解决了“ Cβ-立体选择性问题”。DrDTA对具有吸电子取代基的芳族醛显示出高活性。在优化的反应条件下,获得具有2'-氟或
Diastereo- and Enantioselective Synthesis of β-Hydroxy-α-Amino Acids: Application to the Synthesis of a Key Intermediate for Lactacystin
β-hydroxy-α-amino acids is described. Nucleophilic addition of enolates of tricyclic iminolactones 1a and 1b to aldehydes in the presence of 6 equiv of lithium chloride in THF at −78 °C leads to aldol adducts in good yield (63−86%) and high diastereoselectivity (up to >25:1 dr). Subsequently, hydrolysis of the aldol adducts under acidic conditions leads to the corresponding β-hydroxy-α-amino acids in good yields
Asymmetric synthesis of heteroorganic analogs of natural compounds. 3. General preparative method of diastereo- and enantioselective synthesis of fluorine-containing 2(R), 3(S)-?-phenylserines
作者:V. A. Soloshonok、V. P. Kukhar'、S. V. Galushko、M. T. Kolycheva、A. B. Rozhenko、Yu. N. Belokon'
DOI:10.1007/bf00961372
日期:1991.5
The diastereo- and enantioselective synthesis of the previously unknown 2(R), 3(S)-beta-phenylserines containing fluorine atoms, the O-CHF2-, O-CF3-, and CF3 groups in the benzene ring, was carried out by alkylation of a Ni(II) complex of a Schiff base of glycine with (S)-2-N-(N'-benzylprolyl)aminobenzophenone by fluorine-substituted benzaldehydes. The factors influencing the stereochemical result of the reactions studied are not the steric characteristics of the substituents in benzaldehydes, but their electronic nature.
Edmonds et al., Proceedings of the Society for Experimental Biology and Medicine, 1956, vol. 92, p. 80