不同温度下Cu(Ⅱ)-氨基酸水杨醛席夫碱二元配合物的稳定性

在 15± 0 .1℃ ,2 5± 0 .1℃ ,35± 0 .1℃ ,I =0 .1mol/LKNO3 条件下 ,应用 pH电位滴定法测定了α_氨基酸水杨醛席夫碱的酸离解常数和铜 (Ⅱ )_α_氨基酸水杨醛席夫碱二元配合物的稳定常数 .实验发现 ,在所有温度下 ,二元配合物的稳定性与配体碱性之间均存在良好的直线自由能关系 ,配合物的生成反应是放热反应     

含香兰素和氨基酸新型席夫碱的合成研究

本文报道了由氨基酸钾盐和香兰素合成了4种新的席夫碱．经过实验研究，找出了合成席夫碱的最佳条件，在氨基酸和香兰素投料的量为等物质的量的情况下，用乙醇溶液作溶剂，溶液的pH=7～8，反应温度50～60℃，反应时间为5小时，产率均高于51％，用紫外光谱对产品进行了分析。     

一些土壤样品的氨基酸初步分析

分析了南方的几种自然土壤样品中的氨基酸含量和组成．结果表明，氨基酸含量随深度增加而减少；不同土样的氨基酸组成模式相似，酸性氨基酸占总氨基酸重量的２０％～４０％，中性氨基酸占６０％～７５％，碱性氨基酸仅占１０％以下．同时，还检测到土壤中含有一定量的Ｄ－型氨基酸     

M(Ⅱ)-氨基酸水杨醛席夫碱-ATP三元配合物稳定性研究

用pH电位滴定法测定了Zn^2＋，Cu^2＋，Ni^2＋和Co^2＋与氨基酸水杨醛席夫碱及ATP形成的三元配合物的稳定常数，发现log β111与pk2之间存在很好的线性自由能关系，研究了三元配合物中配体间的疏水相互作用．     

氨基酸的等电点与pKa的关系

根据氨基酸的电离平衡，讨论了碱性和酸性氨基酸的等电点与ｐＫａ的关系，得到氨基酸的等电点的计算公式。     

水溶性SalenMn(Ⅱ)的合成及其对氨基酸的分子识别研究

本文合成并表征了手性席夫碱配体(Salen H2)及其水溶性的锰配合物[Salen Mn(Ⅱ)].用紫外-可见光谱滴定技术测定了主体Salen Mn(Ⅱ)与客体氨基酸(苯丙氨酸和苏氨酸)对映异构体分子间进行识别作用的缔合常数.结果表明:SalenMn(Ⅱ)与系列客体氨基酸作用的配位比均为1∶2,主客体反应均为放热、熵减...     

M(II)-氨基酸水杨醛席夫碱-ATP三元配合物稳定性研究

用pH电位滴定法测定了Zn2+,Cu2+,Ni2+和Co2+与氨基酸水杨醛席夫碱及ATP形成的三元配合物的稳定常数,发现logβ111与pk2之间存在很好的线性自由能关系,研究了三元配合物中配体间的疏水相互作用.     

3种五加中微量元素和氨基酸含量分析

用等离子体发射光谱仪和氨基酸分析仪测定了吴茱萸、细柱五加和华人参木不同部位中的微量元素含量及人体必须的多种氨基酸，结果表明：３种五加中的大部分微量元素分布趋势一致，但华人参木各部位的锰元素含量很高，其叶中的氨基酸含量均高于其它部位４－５倍。     

氨基酸在水溶液中扩散系数的测量

氨基酸的分离及加工过程经常会涉及到扩散问题,但相关的实验数据还远远不能满足需要,因此实验测定氨基酸的扩散系数具有十分重要的意义．利用实时激光全息干涉法对氨基酸在水溶液中的扩散进行了研究,在对实验装置可靠性验证的基础上,测定了L-异亮氨酸、L-丝氨酸、L-苏氨酸和L-精氨酸在298．15 K水溶液中的液相扩散系数,并分析了分子结构和溶液浓度对氨基酸扩散系数的影响．研究结果为优化氨基酸的分离及加工处理过程提供了一些实验依据．     

不带电荷极性氨基酸对兔肝中碱性磷酸酶活性的影响

采用生物化学方法中的有机溶剂分级沉淀法,对碱性磷酸酶进行了分离纯化,用金氏法测定其活性,并用Folin-酚法测定酶含量,然后筛选碱性磷酸酶的最适pH值和最适温度。在此条件下研究不带电荷极性氨基酸对兔肝中碱性磷酸酶活性的影响。结果表明,兔肝中碱性磷酸酶的最适pH值为9.84,最适温度为39℃。在不带电荷极性氨基酸中甘氨酸、苏氨酸、半胱氨酸和天冬酰胺对碱性磷酸酶的活性有不同的抑制作用,而丝氨酸对碱性磷酸酶的活性有激活作用,这说明不带电荷极性氨基酸对酶活性抑制或激活作用与其侧链基团有关。     

封闭体系中氨基酸振荡反应的研究

采用核磁共振及电势法对１０余种氨基酸振荡体系作了较为详尽的研究,获得了适应人体所有氨基酸的振荡器．提出了振荡反应具有活性中心的观点,归纳出经验公式,并得到了振荡能量的计算法．     

电渗析法处理氨基酸废水

对文题进行了研究。结果表明:用电渗析法净化酸性氨基酸(AA)废水,净化后的水质COD约为20mg/L,处理每吨废水的电耗约为1kW·h/m~3;电渗析法可把废水净化和AA浓缩相结合,在操作电压30V,终点电流0.23A,隔室内流速4cm/s,温度21.2℃的条件下,浓缩水和净化水的浓度比达500,浓缩水中AA的浓度为0.1mol。     

THz time-domain spectroscopy of amino acids

The optical characteristics of four kinds of amino acids （tyrosine, arginine, histidine and glutamine） filled with nitrogen at room temperature were studied by THz time-domain spectroscopy （THz-TDS）. Well-resolved absorption and refractive spectrums between 0.I and 2.8 THz were obtained based on the physical model for extracting the optical parameters of materials in THz range. The results not only fill up the spectra gap of amino acids in far-infrared range, supply data for amino acid molecular identification and conformation analysis, but also demonstrate significantly potential to promote the research and application of biological materials in bio-chemical and medical fields by THz-TDS.     

Relative helix-forming tendencies of nonpolar amino acids

An important issue in understanding the relationship between protein sequence and structure is the degree to which different amino acids favour the formation of particular types of secondary structure. Estimates of the 'helix-forming tendency' of amino acids have been made based on 'host-guest' experiments, in which copolymers are made of the amino acid of interest (the 'guest') and a host residue (typically hydroxypropyl- or hydroxybutyl-L-glutamine). Recently, however, short alanine-based peptides were found to form stable monomeric helices in water, contrary to the result predicted from host-guest experiments. We have now measured the helix-forming tendency of five different nonpolar amino acids (Ala, Ile, Leu, Phe, Val) by substituting each in turn for alanine in a 17-residue alanine-based peptide and determining the extent of alpha-helix formation. Our results differ from those of host-guest experiments both in the degree of variation in helix-forming tendency of different amino acids, and in the rank order of the helix-forming tendency. We conclude that the helix-forming tendency of a particular amino acid depends on the sequence context in which it occurs; and the restriction of side-chain rotamer conformations is important in determining the helix-forming tendency.     

Orientation of the peptide formation of N-phosphoryl amino acids in solution

The peptide formation of N-phosphoryl amino acids with amino acids proceeds in aqueous solution without any coupling reagents. After being separated in sephadex gel column, the phosphoryl dipeptides were analyzed by the electrospray ionization tandem mass spectrometry (ESIMS/ MS). The result demonstrates that phosphoryl dipeptides were detected in all the reaction systems. It is found that the formation of N-phosphoryl dipeptides is oriented: the N-terminal amino acid residues of the N-phosphoryl dipeptides are from N-phosphoryl amino acids, and the peptide elongation happened at the C-terminal. Only a-dipeptide, no b-dipeptide, is formed in the N-phosphoryl dipeptides, showing that a-carboxylic group is activated selectively by N-phosphorylation. Theoretical calculation shows that the peptide formation of N-phosphoryl amino acids might happen through a penta-coordinate carboxylic-phosphoric intermediate in solution. These results might give some clues to the study on the origin of proteins and protein biosynthesis.     

Branched chain amino acids and metabolic regulation

Amino acids are fundamental nutrients required for protein synthesis. The branched chain amino acids (BCAAs) leucine, isoleucine, and valine are the most abundant of the essential amino acids. BCAAs have recently been recognized as having functions in processes other than simple nutrition. For example, metabolic diseases are characterized by higher levels of circulating BCAAs. Moreover, supplementation with or deficiency in BCAAs is closely related to the regulation of metabolic homeostasis. Indeed, leucine deprivation induces increased lipolysis and thermogenesis, which result in fat loss, as well as suppressed lipogenesis and enhanced insulin sensitivity in the liver. Accumulating evidence has indicated that several amino acid sensors, including GCN2, ATF4, mTOR, and AMPK, play pivotal roles in the regulation of lipid metabolism, glucose metabolism, and energy homeostasis. Furthermore, the hypothalamus is critical for sensing amino acid levels and mediates the metabolic adaptation of the body upon limitation of essential amino acids (EAAs) through regulating expression of the S6K1, MC4R, and CRH. In this review, we highlight recent studies investigating the cellular mechanisms linking amino acids, amino acid sensors, metabolic regulation, and metabolic diseases. Amino acid sensing and metabolic regulation have become research hotspots in the metabolic field.     

星虫状海葵氨基酸和脂肪酸的组成与含量分析

分析了星虫状海葵的营养成分,干物质中的蛋白质和氨基酸含量分别为62．3％和51．9％;必需氨基酸占氨基酸总量的36．6％,氨基酸分为48。脂肪酸组成具有以下几个特点：26种脂肪酸组成;不饱和脂肪酸(UFA)含量为75．27％,高于饱和脂肪酸(SFA);不饱和脂肪酸中高度不饱和脂肪酸(HUFA)的含量(52．71％)较高;EPA和DHA的含量较高,分别为13．88％和10．98％。星虫状海葵是一种开发前景较好的海产品。     

Racemic amino acids from the ultraviolet photolysis of interstellar ice analogues

The delivery of extraterrestrial organic molecules to Earth by meteorites may have been important for the origin and early evolution of life. Indigenous amino acids have been found in meteorites-over 70 in the Murchison meteorite alone. Although it has been generally accepted that the meteoritic amino acids formed in liquid water on a parent body, the water in the Murchison meteorite is depleted in deuterium relative to the indigenous organic acids. Moreover, the meteoritical evidence for an excess of laevo-rotatory amino acids is hard to understand in the context of liquid-water reactions on meteorite parent bodies. Here we report a laboratory demonstration that glycine, alanine and serine naturally form from ultraviolet photolysis of the analogues of icy interstellar grains. Such amino acids would naturally have a deuterium excess similar to that seen in interstellar molecular clouds, and the formation process could also result in enantiomeric excesses if the incident radiation is circularly polarized. These results suggest that at least some meteoritic amino acids are the result of interstellar photochemistry, rather than formation in liquid water on an early Solar System body.     

Orientation of the peptide formation of N-phosphoryl amino acids in solution

The peptide formation of N-phosphoryl amino acids with amino acids proceeds in aqueous solution without any coupling reagents. After being separated in sephadex gel column, the phosphoryl dipeptides were analyzed by the electrospray ionization tandem mass spectrometry (ESIMS/ MS). The result demonstrates that phosphoryl dipeptides were detected in all the reaction systems. It is found that the formation of N-phosphoryl dipeptides is oriented: the N-terminal amino acid residues of the N-phosphoryl dipeptides are from N-phosphoryl amino acids, and the peptide elongation happened at the C-terminal. Only a-dipeptide, no β-dipeptide, is formed in the N-phosphoryl dipeptides, showing that a-carboxylic group is activated selectively by N-phosphorylation. Theoretical calculation shows that the peptide formation of N-phosphoryl amino acids might happen through a penta-coordinate carboxylic-phosphoric intermediate in solution. These results might give some clues to the study on the origin of proteins and protein biosynthesis.     

不同季节中兰州鲇肌肉水解氨基酸

目的研究兰州鲇(Silurus lanzhouensis)肌肉中常规营养成分和不同季节中肌肉水解氨基酸的组成和含量。方法采用氨基酸自动分析仪测定肌肉中水解氨基酸。结果兰州鲇肌肉中含有18种氨基酸,组成和含量顺序未呈现出季节性变化特点;蛋氨酸、异亮氨酸、亮氨酸、天冬氨酸、丙氨酸这5种氨基酸的含量及氨基酸总量,均随季节的推移呈上升趋势,但在3个季节中仅有秋季显著高于春季(P<0.05);苏氨酸、丝氨酸和谷氨酸等9种氨基酸的含量和必需氨基酸总量等虽有季节性上升趋势,但在3个季节间均无显著差异(P>0.05);胱氨酸、组氨酸和精氨酸等4种氨基酸含量未呈现出季节性变化。结论兰州鲇是一种蛋白质含量较高的经济鱼类,肌肉中水解氨基酸的种类、含量顺序及多数氨基酸的含量在季节变化中有较大的保守性。