氨基酸等电点分离方法的回收率与分离度

以多元酸的分布系数为基础，研究了氨基酸等电点分离方法的回收率和分离度，获得了有应用价值的表达式。     

氨基酸在水或氯化钾水溶液中体积性质的研究

在298.15K和常压下利用密度法测定了十几种α-氨基酸在水或氯化钾水溶液中的表观摩尔体积, 由此得到了各氨基酸的偏摩尔体积和其相应的转移偏摩尔体积,以及氨基酸中侧链对其偏摩尔体积的贡献值。从理论上计算了各氨基酸在上述溶液浓度的增加而增大; 氨基酸共溶质间的相互作用以1:1形式为主; 氨基酸的水化数随盐浓度的增加而减小。对所得结果进行了定性讨论。     

氨基酸在水或氯化钾水溶液中体积性质的研究

在298.15K和常压下利用密度法测定了十几种α-氨基酸在水或氯化钾水溶液中的表观摩尔体积,由此得到了各氨基酸的偏摩尔体积和其相应的转移偏摩尔体积,以及氨基酸中侧链对其偏摩尔体积的贡献值.从理论上计算了各氨基酸在上述溶液中的水化数和体积相互作用参数.结果表明,氨基酸的转移偏摩尔体积值随着盐溶液浓度的增加而增大;氨基酸与共溶质间的相互作用以1∶1形式为主;氨基酸的水化数随盐浓度的增加而减小.对所得结果进行了定性讨论.     

固化pH梯度毛细管等电聚焦整体柱的制备及在蛋白质等电点分析中的应用

通过聚合物原位聚合反应，制备了部分填充的毛细管整体柱。pH 3~10的载体两性电解质被固化在该毛细管整体柱上。在引入八通进样阀、三通阀和四通连接单元的基础上，构建了适用于固化pH梯度毛细管等电聚焦整体柱（M-IPG）的平台。在蛋白质药物测定过程中，用M-IPG柱和羟丙基纤维素（HPC）涂层毛细管柱同时对曲托珠单抗和依那西谱的等电点进行了测定。结果表明，两种等电聚焦柱都能够同时分离混合蛋白质样品并测定蛋白质类药物中单抗和融合蛋白质的等电点（pI），M-IPG柱所测的pI值与HPC涂层毛细管柱测定的结果基本一致，表明了该柱在进一步构建多维分离平台进行蛋白质组学研究方面的潜力。     

温度对水的离子积与溶液酸碱性的pH判据的影响

讨论了温度对水的离子积Kw和溶液酸碱性的pH判据的影响,分析了容易产生的模糊认识.Kw随温度升高显著增大,使溶液呈中性的pH(中性pH = pKw/2)在高温(>25 ℃)和低温区(<25 ℃)分别出现小于和大于7.0的情况.     

氨基酸季铵离子液体水溶液的密度和黏度

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基于p值流程图计算水溶液酸碱度的方法

介绍一种用于酸碱度计算的p值流程图,学生通过回答流程图上的一系列问题,并找到正确的方程式,即可方便地求解常见溶液pH的计算问题,而不需要借助计算器。     

高温水溶液pH值原位测量系统与机理

研制了以氧化钇稳定氧化锆(YSZ)陶瓷薄膜电极为pH电极、外置压力平衡式Ag/AgCl电极为参比电极的高温高压水溶液pH值原位测量系统,测量了H₃BO₃\LiOH水溶液在473.15~573.15 K范围内的pH值,并与热力学计算得到的pH值比较。 结果表明,当温度高于548.15 K时,测量系统可以实现pH值的准确测量;而低于此温度时,由于YSZ陶瓷膜内阻过大,测得的pH值与理论计算值存在偏差,且随温度的降低,测量偏差增大。 讨论了该系统的pH值测量机理。     

氨基酸存在形式的分布及滴定法测定的可行性

讨论水溶液中各类氨基酸存在形式的分布及用传统滴定分析法测定的可行性,用谷氨酸、精氨酸、组氨酸及丝氨酸验证了讨论结果。结论：酸性氨基酸可以用碱滴定;碱性氨基酸可以用酸滴定;中性氨基酸既无法用碱滴定,也无法用酸滴定。     

等电点时氨基酸溶解度最小之数学推证

利用中性氨基酸在等电点时各型体的平衡关系,从数学角度证明了一定温度下其两性离子浓度最大,分布系数最大,溶解度最小,并由相关氨基酸溶液中各型体的分布系数和溶解度图得到佐证。对苏教版《有机化学基础》中氨基酸的分离进行了解读。     

氨基酸缓蚀剂在盐酸溶液中对钢的缓蚀作用

应用极化曲线、电化学阻抗谱等测试技术,研究了以谷氨酸作缓蚀剂在10%盐酸介质中对X65钢的缓蚀作用,测试腐蚀参数包括腐蚀电位(Ecorr)、极化电阻(Rp)、缓蚀效率(η)等.研究表明:该缓蚀剂是一种抑制阴极为主的混合型缓蚀剂,在较低的浓度具有良好缓蚀效果;缓蚀效率随着浓度的增加而提高,并在0.3g.L-1时达到最大值(90%以上).     

The Isoelectric Point and the Points of Zero Charge of Fe-Al-Mg Hydrotalcite-like Compounds

The relation of the isoelectric point (IEP) and the point of zero net charge (PZNC) of the hydrotalcite-like compounds was discussed. It was found that the IEP does not equal to the PZNC and the IEP is higher than the PZNC. The structural positive charges existing in the HTlc,which cause the difference between the IEP and the PZNC. The effects of the structural positive charges of the HTlc on its IEP and PZNC are the same as the specific adsorption of metal cations.     

Zn-Al类水滑石零净电荷点及等电点研究

用非均相共沉淀法合成了系列Zn-Al类水滑石(HTlc)样品,研究发现A1／(Zn Al)摩尔比(x)在0．31～0．52范围内可得到纯类水滑石相．用电势滴定法和显微电泳法分别测定了5个纯Zn-Al HTic样品的零净电荷点(PZNC)和等电点(IEP),以考察结构电荷对PZNC和IEP的影响．研究发现随结构正电荷密度的增加,PZNC和IEP均降低;IEP高于PZNC,且随结构正电荷密度的降低,IEP与PZNC的差值也降低,表明IEP与PZNC的差异来自结构电荷的影响．结构正电荷对HTlc的IEP与PZNC相对大小的影响与高价阳离子特性吸附的影响一致．初步探讨了结构电荷对PZNC和IEP的影响机理．     

多肽净电荷数及等电点的计算

多肽净电荷数及等电点的计算许旭（中国药科大学药物分析教研室，南京，２１０００９）罗国安，林炳承（清华大学化学系）（中国科学院大连化学物理研究所）关键词毛细管区带电泳，多肽，净电荷数，等电点考察多肽在毛细管区带电泳（ＣＺＥ）中的迁移时，必须知道其在分析...     

磷酸和氢氧化钠混合后溶液的主要组成及pH计算*

磷酸和氢氧化钠混合后溶液的组成较为复杂,氢离子浓度的计算较为繁琐。但在pH的近似计算中,通常只需考虑2者混合后溶液的主要组成,根据主要组成再选择相应的公式计算即可,因此分析混合后溶液的主要组成成为此类溶液氢离子浓度计算的关键。首先分析了磷酸和氢氧化钠以不同的物质的量之比混合后溶液的主要组成,重点讨论和导出了2者混成不同缓冲溶液的有关计算公式,公式规律性强,简单实用,易于掌握和应用。     

Ferroptosis-Inhibitory Difference between Chebulagic Acid and Chebulinic Acid Indicates Beneficial Role of HHDP

The search for a safe and effective inhibitor of ferroptosis, a recently described cell death pathway, has attracted increasing interest from scientists. Two hydrolyzable tannins, chebulagic acid and chebulinic acid, were selected for the study. Their optimized conformations were calculated using computational chemistry at the B3LYP-D3(BJ)/6-31G and B3LYP-D3(BJ)/6-311 + G(d,p) levels. The results suggested that (1) chebulagic acid presented a chair conformation, while chebulinic acid presented a skew-boat conformation; (2) the formation of chebulagic acid requires 762.1729 kcal/mol more molecular energy than chebulinic acid; and (3) the 3,6-HHDP (hexahydroxydiphenoyl) moiety was shown to be in an (R)- absolute stereoconfiguration. Subsequently, the ferroptosis inhibition of both tannins was determined using a erastin-treated bone marrow-derived mesenchymal stem cells (bmMSCs) model and compared to that of ferrostatin-1 (Fer-1). The relative inhibitory levels decreased in the following order: Fer-1 > chebulagic acid > chebulinic acid, as also revealed by the in vitro antioxidant assays. The UHPLC–ESI-Q-TOF-MS analysis suggested that, when treated with 16-(2-(14-carboxytetradecyl)-2-ethyl-4,4-dimethyl-3-oxazolidinyloxy free radicals, Fer-1 generated dimeric products, whereas the two acids did not. In conclusion, two hydrolyzable tannins, chebulagic acid and chebulinic acid, can act as natural ferroptosis inhibitors. Their ferroptosis inhibition is mediated by regular antioxidant pathways (ROS scavenging and iron chelation), rather than the redox-based catalytic recycling pathway exhibited by Fer-1. Through antioxidant pathways, the HHDP moiety in chebulagic acid enables ferroptosis-inhibitory action of hydrolyzable tannins.     

Electrochemical Reactions During Isoelectric Focusing and Their Role in Establishment of the pH Gradient

The process occurring as the background to IEF is electrolysis of water. During IEF the yield of water ions decreases, following a non-linear relationship similar to that of the current. Different extents of acidification and basification of the electrode solutions, causing a drift of the pH gradient, were observed. We derived a relationship underlying this process which enables calculation of the electrode current. By using a novel approach we showed that the sum of the pH of distilled water electrode solutions at the end of the IEF process tends to the ionic product of water.     

Isoelectric focusing in immobilized pH gradients of phosphoglucomutase and esterases from the spiny lobster

A method is described for detecting polymorphisms of cephalothorax and tail homogenates of 25 puerulus staged Panulirus argus in phosphoglucomutase (PGM) and esterases. Isoelectric focusing in immobilized pH gradients was used. In the pH 6.0-8.0 interval for phosphoglucomutase and in the pH 3.5-5.0 and 4.2-4.9 ranges for esterases, both enzymes appeared as polymorphic band patterns. These could be explained by one locus with 2 alleles for phosphoglucomutase and 3 loci with 2, 3 and 4 alleles for esterases. Esterases exhibit a more extensive polymorphism in immobilized pH gradients than in polyacrylamide gel electrophoresis.