Synthesis and Crystal Structure of N-[（2S）-4-bromo-2-（L-menthyloxy）-5-oxo-2,5-dihydro-3-furyl]-L-leucine

Starting from(5S)-(L-menthyloxy)-3,4-dibromo-5H-furan-2-one and L-leucine,the title compound N-[(2S)-4-bromo-2-(L-menthyloxy)-5-oxo-2,5-dihydro-3-furyl]-L-leucine 5(C20H32BrNO5,Mr = 446.37) was obtained in one-pot process via the tandem Michael addition-elimination reaction in the presence of potassium hydroxide.The chemical structure and absolute configuration of the title compound were confirmed via rotation,UV-Vis,FT-IR,1H NMR,13C NMR,MS and elemental analysis,especially by the X-ray single-crystal diffraction.The crystal crystallizes in an orthorhombic system,space group P212121 with a = 12.5249(16),b = 19.005(3),c = 19.719(3) ,V = 4693.7(10) 3,Z = 8,Dc = 1.263 g/m3,μ = 1.778 mm-1,F(000) = 1872,the final R = 0.0617 and wR = 0.1576 for 3967 observed reflections(I > 2σ(I)).X-ray analysis reveals that the title compound has two independent molecules in the asymmetric part of the unit cell with the two five-membered furanones being almost planar.The essential part of the electron delocalization is concentrated in the N(1),C(3),C(1),C(37) and O(7) region and N(2),C(28),C(27),C(30) and O(4) region in the other molecule respectively,but does not take place at the expense of delocalization within the ester function.     

手性温敏凝胶 P(NIPAM-co-NALL)的制备及识别性能

以L-亮氨酸(L-Leu)为手性源, 经酯化和缩合等步骤制备手性单体(NALL), 以该单体为手性识别基团, 在交联剂N,N'-亚甲基双丙烯酰胺和引发剂偶氮二异丁腈的作用下, 与N-异丙基丙烯酰胺(NIPAM)以不同的质量比发生自由基共聚, 制备了一系列新型手性温敏水凝胶P(NIPAM-co-NALL), 其结构经红外光谱确证. 相比于PNIPAM水凝胶, 疏水性单体NALL的引入使 P(NIPAM-co-NALL)凝胶的温敏性下降. 以D, L-苯丙氨酸为模型药物对P(NIPAM-co-NALL)凝胶的手性识别和拆分性能进行研究, 结果表明, 手性温敏凝胶对D型对映体具有选择吸附性, 且吸附量随着手性单体含量的增加而增加; 提高温度(40 ℃)有利于手性温敏凝胶对D, L-苯丙氨酸的手性识别和拆分. P(NIPAM-co-NALL)凝胶在重复使用后依然具有手性识别性能, 但其吸附量随着使用次数的增加而下降, 3次重复使用后吸附量下降到原来的27.6%.     

反萃分散组合液膜分离提取氨基酸

建立了分离提取蛋氨酸、亮氨酸、苯丙氨酸和色氨酸的磷酸二（2-乙基己基）酯(D2EHPA) 煤油-HCl反萃分散组合液膜体系,考察了料液相pH值、载体D2EHPA浓度、液膜相与反萃相体积比、反萃相组成、料液相与反萃分散相流速、传输时间以及支撑膜重复使用次数对氨基酸渗透系数和传输效率的影响。 在优化的条件下,建立的反萃分散组合液膜体系对4种氨基酸均可以获得大于35%的传输效率,其中色氨酸和亮氨酸的传输效率超过了79%,且传输效率呈Et,Trp＞Et,Leu＞Et,Phe＞Et,Met的趋势。 支撑膜重复使用25次,对氨基酸的传输效率没有明显改变。建立的液膜体系对考察的氨基酸展示了较高传输效率和优越的传输选择性,是一种简单和环境友好的分离技术。     

New optically active poly（amide-imide）s derived from N, N′-（4,4-diphthaloyl）-bis-L-leucine and hydantoin derivatives： Synthesis and properties

Six new optically active poly(amide-imide)s(5a-f) were synthesized through the direct polycondensation reaction of N,N'-(4,4'- diphthaloyl)-bis-L-leucine(3) with six hydantoin derivatives(4a-f).Triphenyl phosphite(TPP)/pyridine in the presence of calcium chloride(CaCl_2) and N-methyl-2-pyrrolidone(NMP) were successfully applied for direct polycondensation.The polycondensation reactions produce a series of new poly(amide-imide)s(5a-f) in high yields,and inherent viscosity between 0.42 and 0.55 dL/g.The re...     

亮氨酸的荷移分光光度法测定

用分光光度法研究了亮氨酸与四氯对苯醌的荷移反应.实验结果表明,在硼砂缓冲溶液中,两者于60℃水浴中恒温50min即可形成稳定的荷移络合物,其λmax=350nm,络合物组成比为1:1,表观摩尔吸光系数ε=2×104 L·mol-1·cm-1,浓度在0.16-8μg/mL,范围内符合比耳定律,回收率在99.6%-101.0%之间,相对标准偏差在0.6%以内.     

DNA结合蛋白结构域的研究进展*

本文综述了3种DNA结合蛋白结构域-螺旋一转折一螺旋、亮氨酸拉链、锌指近年来的研究进展。参考文献65篇。     

低温等离子体作用下亮氨酸转化路径的密度泛函理论研究

目前低温等离子体技术在处理固体废弃物方面已得到广泛关注,本研究基于密度泛函理论(DFT),在B3LYP/6-31G(d,p)的水平上模拟计算了污泥中蛋白质模型化合物亮氨酸(LEU)在低温等离子体中的转化路径,包括脱氨优先机理、脱羧优先机理、其余C-C键断裂优先机理等七条主要路径.结果表明,亮氨酸易脱除氨基、羧基生成C5...     

亮氨酸、异亮氨酸的结构与热力学性质研究

用ＭＮＤＯ法研究了亮氨酸、异亮氨酸分子几何构型与热力学性质之间的关系，讨论了分子中非键合原子之间的相互作用．计算表明，Ｎ—Ｈ…Ｏ＝Ｃ分子内氢键不易形成．用各种方法计算了它们的气态生成焓，并加以比较．还发现在异亮氨酸中１，４－相互作用引起的扭曲效应是存在的，文中给出其校正值［Ｓ＇］．     

水溶液中甘氨酰替亮氨酸与Ho(ClO43和Yb(ClO43相互作用的NMR研究

本文用¹³C NMR方法研究了水溶液中三价顺磁性稀土离子Ho³⁺和Yb³⁺与二肽甘氨酰替亮氨酸之间的相互作用。对稀土诱导位移中的接触位移和偶极位移进行了分离。实验表明,与羧基相连的碳核所受的接触作用很大,因此不能把镱诱导的位移直接用于肽的构象分析。在水溶液中,肽通过羧基与稀土离子配位,在弱酸性条件下肽键和氨基均不参与配位。根据结构因子确定了肽在溶液中的构象,结果表明,分子片段C1-C2-C5-C6,C2-N-C3-C4和C2-C5-C6-C8为反式,而C2-C5-C6-C7和C1-C2-N-C3成旁式。     

Synthesis of optically active polymers bearing amino acid moieties by atom transfer radical polymerization

We report here an approach toward the synthesis of optically active polyacrylamide bearing amino acid moieties, poly[N- methacryloyl L-leucine methyl ester] (PMALM), with controlled average number molecular weight (Mn) and relatively narrow polydispersity index (PDI, Mw/Mn < 1.3) by atom transfer radical polymerization (ATRP) using initiating system methyl 2- bromopropionate/CuBr/tris(2-dimethylaminoethyl) amine. The optical properties of the resulting polymers were evaluated fromspecific optical rotation value and CD spectra.