New Model for Polymerization of Oligomeric Alcohol Dehydrogenases into Nanoaggregates

Polymerization and self-assembly of proteins into nanoaggregates of different sizes and morphologies (nanoensembles or nanofilaments) is a phenomenon that involved problems in various neurodegenerative diseases (medicine) and enzyme instability/inactivity (biotechnology). Thermal polymerization of horse liver alcohol dehydrogenase (dimeric) and yeast alcohol dehydrogenase (tetrameric), as biotechnological ADH representative enzymes, was evaluated for the development of a rational strategy to control aggregation. Constructed ADH nuclei, which grew to larger amorphous nanoaggregates, were prevented via high repulsion strain of the net charge values. Good correlation between the variation in scattering and λ ⁻² was related to the amorphousness of the nanoaggregated ADHs, shown by electron microscopic images. Scattering corrections revealed that ADH polymerization was related to the quaternary structural changes, including delocalization of subunits without unfolding, i.e. lacking the 3D conformational and/or secondary-ordered structural changes. The results demonstrated that electrostatic repulsion was not only responsible for disaggregation but also caused a delay in the onset of aggregation temperature, decreasing maximum values of aggregation and amounts of precipitation. Together, our results demonstrate and propose a new model of self-assembly for ADH enzymes based on the construction of nuclei, which grow to formless nanoaggregates with minimal changes in the tertiary and secondary conformations.     

Metal-Free Deoxygenation of Amine N-Oxides: Synthetic and Mechanistic Studies

We report herein an unprecedented combination of light and P(III)/P(V) redox cycling for the efficient deoxygenation of aromatic amine N-oxides. Moreover, we discovered that a large variety of aliphatic amine N-oxides can easily be deoxygenated by using only phenylsilane. These practically simple approaches proceed well under metal-free conditions, tolerate many functionalities and are highly chemoselective. Combined experimental and computational studies enabled a deep understanding of factors controlling the reactivity of both aromatic and aliphatic amine N-oxides.     

1-苯基-3-甲基-4-苯甲酰基吡唑啉酮-5与胺类缔合研究

1-苯基-3-甲基-4-苯甲酸基毗哇琳酮一5（HPMBP）是一类酸性鳌合革取剂,已广泛用于多种元素分离、分析研究［'j．它不仅在单独使用时能很好地革取金属,而且在与有机胺类共同使用时对稀土元素、过渡金属元素有明显的快同革取性能L'·'］．因此研究HPMBP与胺类的相互作用对于分析产生协同作用的原因,改善革取性能是很有必要的．1实验部分1．1试剂HPMBP,化学纯（北京试剂厂）;三千胺（TOA）,FLUKA进口分装试剂,纯度大于99％;伯胺N1923,工业级（上海有机化学研究所化学实验厂）,经减压（267～533Pa）蒸馏,收集413～459K馏…     

叔铵盐—烷烃—醇—水四元体系的热力学函数与结构研究

叔铵类(R_3N)萃取剂萃取金属离子需在酸性介质中进行,与无机酸先形成铵盐(属阴离子表面活性剂类),然后与金属配阴离子进行阴离子交换反应。而将R_3N制成无机酸盐,作为表面活性剂以微乳液为模型对其进行热力学函数与结构研究尚未见报道。 本文制备了TOA·HCl、N235·HCl、N235·HNO_3与N235·HClO_44种叔铵无机酸盐,测定了叔铵盐的界面化学性质。以w/o型微乳液的球形颗粒结构为模型,用稀释法测定了叔铵盐(TOA·HCl,N235·HCl,N235·HNO_3,N235·HClO_4)-烷烃-醇-水四元均相透明体系的结构参数;并用不同醇时,醇由油相(o)转移至界面层(i)的标准自由能变(?)结果表明其结构“颗粒”半径小于0.5nm,表面活性剂叔铵盐的平均聚集数小于0.05,应属醇的反向胶团。 1 实验 1.1 试剂 三正辛胺(TOA,德国);N235(R_3N,R=C_5—C_(10),大连油脂化学厂)。叔铵盐TOA·HCl分别用干法(D)与湿法(W)制备。向TOA中通入干燥HCl气体至饱和,再加入分析量的TOA中和过量的HCl,制得TOA·HCl(D).TOA与过量10mol/L盐酸振荡平衡,再加入分析量的TOA中和过量酸制得TOA·HCl(W),样品均为淡黄色蜡状固体,N235·HCl、N235·HNO_3、N235·HClO_4均用湿法制备。其它试剂均为A.R.级,未进一步处理,水为二次蒸馏水。     

适于测定苄胺的可逆光敏膜的研究

本文报道了一种测定苄胺的可逆光敏膜.将作为苄胺离子载体的联萘冠醚和亲脂的pH指示剂,结合在增塑的PVC膜中,苄胺离子与氢离子在膜相的竞争引起膜的吸光值变化.报道了该传感器的响应特性,推导了有关的理论关系式.     

层状磷酸盐在有机胺溶液中的胶体化和稳定性研究

系统地研究了层状磷酸锆（α－ＺｒＰ）、磷酸锡（α－ＳｎＰ）和磷酸钛（α－ＴｉＰ）在有机胺水溶液中的胶体化（即层板剥离）和水解状况。发现磷酸盐在有机胺嵌入而胶体化的同时，层板表面的ＨＰＯ４＾２－和金属离子发生水解而脱离，ＨＰＯ４＾２－的脱离先于金属离子，ＨＰＯ４＾２－水解度超过４０％则磷酸盐层状结构破坏严重。在相同的有机胺溶液中，不同磷酸盐的水解和胶体化状况不同，其中磷酸钛的水解最严重层板最信打开，     

Amine

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Amine

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Amine

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N,N-二甲基正十二烷基胺/无机含氧酸体系的相态结构研究

利用拟三元相图法研究了N,N-二甲基正十二烷基胺(DMDA)多元体系的相态结构,并用电导、偏光显微镜以及红外、紫外可见光谱等手段进行了表征.发现N,N-二甲基正十二烷基胺体系随水相含量的增加,铵盐发生不同形式的有序缔合,分别形成了W/O型微乳液、“节-结”型链状缔合体、层状液晶和O/W型微乳液;在层状液晶中,SO₄^2-主要以桥式双齿配位形式存在,中性胺分子有利于体系中液晶的形成;层状液晶于500nm波长处有一吸收峰,在430nm附近发生“光短路”现象,该现象可能对测定层状液晶的层间距有重要意义.     

Aliphatische Amine

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Sympathicomimetische Amine

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Aliphatische Amine

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Structure and Catalytic Mechanism of 3-Ketosteroid Dehydrogenases

3-Ketosteroid dehydrogenases (KSTDs) are FAD-dependent enzymes that introduce a double bond in the A ring of 3-ketosteroid substrates to initiate degradation of the steroid nucleus. Δ¹-KSTD desaturates the C1-C2 bond of the steroid, while Δ⁴-KSTD targets the C4-C5 bond. Crystal structures with bound products showed that Δ¹- and Δ⁴-KSTD use different amino acid residues to catalyze an otherwise mechanistically very similar reaction (Δ¹-KSTD: Tyr318, Tyr119, and Tyr487; Δ⁴-KSTD: Ser468, Tyr319, and Tyr466). However, the substrates are rotated by ∼40° about an axis perpendicular to their plane to bring the target bond (C1-C2 or C4-C5) in the right position.