(Ni-Sn-M_xO_y)/Pb改性复合电极电解合成L-半胱氨酸的反应

在（Ｎｉ－Ｓｎ）／Ｐｂ合金修饰电极中添加某些金属氧化物进行改性,用于电解合成Ｌ－半胱氨酸反应。结果证明,添加ＷＯ３后电极反应活性大大加强,反应同期转化率有较大提高,选择性也有所提高,添加稀土金属氧化物能有效降低反应阴极过电位,使反应选择性有所提高,但是电极稳定性还有待改善。     

N-乙酰-L-半胱氨酸的合成及其在医药上的应用

概述了近几十年来国内外关于Ｎ－乙酰－Ｌ－半胱氨酸的合成方法及其在医药上的应用。     

电渗析法分离提纯N-乙酰-L-半胱氨酸研究

使用我校由辐射法制备的高性能离子交换膜ＨＦ—１及ＨＦ—２,采用电渗析技术对合成所得的Ｎ－乙酰－Ｌ－半胱氨酸进行了分离提纯,脱盐率＞１５％,损失率＜１５％,为工业化应用提供了依据。     

L-半胱氨酸修饰碳纳米管的合成、表征及电化学性质

通过对碳纳米管氧化,合成了L-半胱氨酸修饰碳纳米管。运用红外、差热-热重分析、透射电镜对该复合物进行了表征。借助循环伏安法研究了其电化学性质。结果表明,碳纳米管的掺入极大地提高了L-半胱氨酸在金电极表面的电子传输速率和电流响应,同时也有利于L-半胱氨酸的电氧化,对L-半胱氨酸的氧化具有催化作用。     

L-酪氨酸合成L-多巴的研究

<正> L-酪氨酸是许多农副产品的蛋白质的组成之一,在利用某些农副产品作原料生产所需产品时,往往有大量酪氨酸从废液、废渣中被丢弃,例如:用毛发制备胱氨酸,国内已年产胱氨酸几百吨,而毛发中含2—3％的酪氨酸,大都从废液中排掉,茧丝工业的废水中和蚕蛹中都含有不少酪氨酸。L-多     

从生产半胱氨酸的废母液中回收胱氨酸的工艺研究

研究了一种从生产半胱氨酸的废母液中回收胱氨酸的工艺,介绍了工艺过程并讨论了其主要原理及影响因素。该方法工艺简单,操作方便,对设备的要求低,而回收率、产品含量均较高,是一种回收利用氨基酸、减少环境污染的好方法。     

比色法测定复合氨基酸注射液中的N-乙酰-L-半胱氨酸

根据Ｎ－乙酰－Ｌ－半胱氨酸与氯化钯（ＰｄＣｌ２）反应,生成一种稳定的黄色化合物,我们建立了比色测定复合结晶氨基酸注射液中的ＮＡＣ的方法。测定波长为３７５ｎｍ,检测结果重现性好,变异系数是３．９％,回收率范围在９３．１％～１００．２％之间,检测下限为０．１６３μｇ／ｍｌ。该方法比经典的电量滴定法灵敏度高、精确性好,较高压液相色谱法操作简便、费用低。     

双酶电极法测定L-苯丙氨酸的研究

本文以Ｃｌａｒｋ氧电极为基础,把水杨酸羟化酶和苯丙氨酸脱氨酶同时固定在氧电极的表面,制成了双酶生物传感器。在磷酸缓冲液中,水杨酸浓度为０．５ｍｍｏｌ／Ｌ,烟酰胺腺嘌呤二核甘酸（ＮＡＤ＾＋）的浓度为１．０ｍｍｏｌ／Ｌ,其响应电流的变化对应反池中Ｌ－苯丙氨酸的浓度在０－０．１５ｍｍｏｌ／Ｌ之内有良好的线性范围。     

多聚唾液酸对L-天冬酰胺酶的修饰及修饰酶特性研究

来源于大肠杆菌 (Ｅ .ｃｏｌｉ)的Ｌ 天冬酰胺酶是治疗淋巴性白血病和恶性淋巴肿瘤的有效酶制剂 ,已应用于临床。该酶与其他蛋白质类药物一样 ,在临床应用中存在两个常见问题 :一是酶制剂在体内易被降解 ,导致半衰期短 ;二是免疫原性。为了解决上述问题 ,人们用亲水性的大分子如血清蛋白、右旋糖苷和单甲氧基聚乙二醇 (ｍＰＥＧ)对该酶进行修饰。其中ｍＰＥＧ[1] 修饰后的Ｌ 天冬酰胺酶的抗原抗体结合能力完全消失 ,免疫原性下降 ,且体内半衰期延长 ;但酶活力只有天然酶的 8%～ 14% ,且ｍＰＥＧ在人体组织中无法降解 ,目前尚难评估长期使用…     

N-乙酰-L-半胱氨酸合成新工艺

研究了一步合成法生产 N-乙酰 -L-半胱氨酸的工艺 ,介绍了工艺过程并讨论了主要影响因素。该方法简单 ,操作方便 ,生产周期短 ,反应选择性好 ,产品得率及纯度很高 ,是一种具有应用价值的新方法     

尿酸在聚6-甲基香豆素修饰的玻碳电极上的电化学行为

制备了聚6-甲基香豆素修饰玻碳电极,研究了尿酸(UA)在该修饰电极上的电化学行为。实验结果表明:在pH=5.0的磷酸盐缓冲溶液中,扫描速率为50mV/s时,尿酸在修饰电极上于0.352V处产生一个灵敏的氧化峰,在0.278V处有一弱的还原峰。经线性扫描伏安法测定,氧化峰电流与尿酸浓度在2.5×10-6～1.0×10-5mol/L范围内表现出良好的线性关系,检出限为1.0×10-6mol/L。将修饰电极在常温下放置50d及将体系温度升高到75℃时,修饰电极对尿酸的响应电流大体不变,结果满意。     

Cysteine Racemization in Peptide Synthesis: A New and Easy Detection Method

A new method has been developed for the rapid determination of D-cysteine contents in synthetic peptides. It is based on the reduction of cystine residues, when present, with tris- alkylphosphines, selective derivatization of the cysteine residues with 4-vinylpyridine, followed by acid hydrolysis of the (4-pyridylethyl)cysteine –peptides. Baseline enantiomeric resolution of theD ,L -S-β-(4-pyridylethyl)cysteine, and thus quantification ofD - enantiomer contents at levels ≤1%, is easily achieved by capillary zone electrophoresis exploiting the host–guest complexation principle with crown ethers or by gas chromatography on chiral glass capillary columns upon conventional derivatization of the hydrolysate. The acid-stability of the (4-pyridylethyl)cysteine derivative prevents racemization via thiazoline intermediates and allows for standardization of the acid hydrolysis-dependent racemization.     

用钴卟啉修饰电极催化测定多巴胺等神经递质

将5, 10, 15, 20－四－（3－甲氧基－4－羟基苯基）卟啉钴（CoTMHPP）修饰在玻碳电极表面,制备成对多巴胶等神经递质有高灵敏度响应的CoTMHPP修饰电极．电极具有灵敏度高、响应快、稳定性好等特点．电极响应时间小于10s,儿茶酚类化合物的检测浓度为10^-6mol／L．     

Cysteine proteinases of microorganisms and viruses

This review considers properties of secreted cysteine proteinases of protozoa, bacteria, and viruses and presents information on the contemporary taxonomy of cysteine proteinases. Literature data on the structure and physicochemical and enzymatic properties of these enzymes are reviewed. High interest in cysteine proteinases is explained by the discovery of these enzymes mostly in pathogenic organisms. The role of the proteinases in pathogenesis of several severe diseases of human and animals is discussed.     

高半胱氨酸膳食对小鼠生长和免疫力的影响

探讨了高半胱氨酸膳食对小鼠生长及对外来抗原刺激产生抗体的免疫力的影响。实验取小白鼠32只,随机分为高半胱氮酸组(H)和对照组(C)各16只。H组每天给予含半胱氨酸质量分数为3％的饲料,分别在1、4、8周对其腹腔注射牛血清白蛋白,在第9周处死动物,取血测量血清抗体效价。结果显示实验组生长缓慢,血清抗体效价显著高于对照组,表明高半胱氨酸膳食可提高小鼠血清抗体效价,但高含量的半胱氨酸对小鼠生长有抑制作用。     

On the Dynamical Behavior of the Cysteine Dioxygenase‐l‐Cysteine Complex in the Presence of Free Dioxygen and l‐Cysteine

In this work, viable models of cysteine dioxygenase (CDO) and its complex with l ‐cysteine dianion were built for the first time, under strict adherence to the crystal structure from X‐ray diffraction studies, for all atom molecular dynamics (MD). Based on the CHARMM36 FF, the active site, featuring an octahedral dummy Fe(II) model, allowed us observing water exchange, which would have escaped attention with the more popular bonded models. Free dioxygen (O₂) and l ‐cysteine, added at the active site, could be observed being expelled toward the solvating medium under Random Accelerated Molecular Dynamics (RAMD) along major and minor pathways. Correspondingly, free dioxygen (O₂), added to the solvating medium, could be observed to follow the same above pathways in getting to the active site under unbiased MD. For the bulky l ‐cysteine, 600 ns of trajectory were insufficient for protein penetration, and the molecule was stuck at the protein borders. These models pave the way to free energy studies of ligand associations, devised to better clarify how this cardinal enzyme behaves in human metabolism.     

Cysteine inhibits amyloid fibrillation of lysozyme and directs the formation of small worm‐like aggregates through non‐covalent interactions

In this article, we discuss the effects of amino acids on amyloid aggregation of lysozyme. l ‐cysteine (Cys) dramatically inhibited fibrillation of lysozyme, whereas other amino acids (including l ‐arginine) did not. In the presence of Cys, the aggregation pathway of lysozyme shifted from fibrillation to the formation of the small worm‐like aggregates with unfolding. The interaction between Cys and lysozyme was observed to be non‐covalent, suggesting that the thiophilic interaction between the thiol group on the side chain of Cys and the core sequence of lysozyme significantly contributes to the inhibition of amyloid aggregation. These findings provide a new basis for the design of a biocompatible additive to prevent amyloid fibrillation. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:470–478, 2014