Simultaneous determination of allantoin, choline and L-arginine in Rhizoma Dioscoreae by capillary electrophoresis

A rapid, easy and reproducible capillary electrophoresis (CE) method for the simultaneous determination of allantoin, choline and arginine in Rhizoma Dioscoreae was developed first time. Under the optimum condition, the three analytes could be well separated within 5 min in a 70 cm (60 cm effective length) x 75 microm i.d. capillary. The relative standard deviations for both migration time and peak height were less than 3.20%. The linear response range was 5.0-150, 0.9-100 and 1.0-200 microg/ml for arginine, choline and allantoin, respectively. The detection limit of three components was 2.0, 0.4 and 0.5 microg/ml for arginine, choline and allantoin, respectively. Contents of arginine, choline and allantoin in the crude drug of Rhizoma Dioscoreae could be easily determined by the proposed method with satisfactory results.     

Papainkatalysierte kinetisch kontrollierte Peptidsynthese. Verwendung von Alkylestern des Arginins als Aminokomponente

Summary The papain-catalyzed reaction of esters of Z-alanine with various arginine esters was investigated. Using H-Arg-OPr ⁱ as a nucleophile the expected dipeptide product results in high yield. Otherwise, reactions with arginine esters of primary alkohols provide products undergoing further reactions. This allows the synthesis of N-protected peptide esters containing two or more arginine residues in a one-step reaction. The influence of reaction conditions on the process was investigated.

AbkürzungenDie IUPAC/IUB-Regeln für Aminosäure- und Peptidderivate wurden befolgt; vgl. Eur. J. Biochem.53, 1 (1975). Die verwendeten Aminosäuren hatten (L)-Konfiguration.-Glo-Gly-OH=Glykolylglycinester,-OCam=Carboxamidomethylester, -OBu ⁱ=Isobutylester,-OMe=Methylester,-OPr ⁱ=Isopropylester,Z=Benzyloxycarbonyl.     

L-精氨酸·氟硼酸加合物的X射线粉末衍射分析

采用X射线粉末衍射法对L-精氨酸·氟硼酸加合物进行了分析.数据收集范围在2θ角从7°到80°(共64个观测点).采用最小二乘法对该加合物粉末衍射的晶胞参数进行了计算,实验表明:该加合物为正交晶系,空间群P212121,晶胞参数a=0.50702(6)nm,b=1.37288(12)nm,c=1.64880(15)nm,V=1.147713nm3;Z=4;ρ=1.52g/cm3,粉末衍射分析的结果与单晶结构数据相吻合.     

碱性蛋白质毛细管电泳分离研究

碱性蛋白质毛细管电泳分离研究任吉存，邓延倬，程介克（武汉大学化学系分析测试科学系，武汉，４３００７２）关键词毛细管电泳，碱性蛋白质，吸附，精氨酸，赖氨酸蛋白质的吸附作用严重影响了毛细管电泳分离蛋白质的重现性［１］．为此，人们寻找各种途径来克服蛋白质的...     

Synthesis of C methylated carboxylic acids: isosteres of arginine and lysine for use as N-terminal capping residues in polypeptides

Replacement of the N-terminal α-amine with the isosteric methyl functionality in bioactive peptides can influence various pharmacokinetic parameters, including hydrophobicity and stability. C^α methylated amino acid analogues are thus of great interest to expand the repertoire of nonnatural synthons available as N-terminal ‘capping’ residues for peptide-based drug design. Several novel arginine and lysine analogues stereoselectively modified in the C^α position with a methyl group in place of the α-amine were prepared.     

精氨酸残基在质子化多肽RRMKWKK的气相碰撞诱导解离过程中的作用

用ESI/MS-MS方法研究了质子化多肽RRMKWKK 在低能气相碰撞诱导解离(CID)条件下的碰撞能和解离路径. 研究结果表明, [M+2H]2+和[M+3H]3+的CID断裂曲线和断裂位点相似. 但质子化多肽所含正电荷个数不同时, 产生同一碎片离子的初始碰撞能不同. 碱性氨基酸残基精氨酸(Arg)的支链是多肽RRMKWKK质子化时质子优先结合的位点, 导致含有Arg的多肽在气相碰撞诱导解离条件下解离时需要较高的碰撞能. 在用质谱方法研究含精氨酸残基的多肽时应选择质子个数比多肽中Arg个数多1个的母体离子. 质子化多肽RRMKWKK的结构AM1计算结果表明, 质子化RRMKWKK中两个相邻精氨酸在空间上相互分离, 库伦斥力的影响不足以改变质子的优先结合位点.     

基于化学衍生和CID碎裂模式鉴定蛋白精氨酸-ADP-核糖基化的新方法

建立了一种新的基于碰撞诱导解离（CID）碎裂模式鉴定精氨酸-腺苷二磷酸（ADP）-核糖基化多肽的新方法. 首先,在碱性条件下将精氨酸-ADP-核糖基化血管紧张素-Ⅰ转变为鸟氨酸化血管紧张素-Ⅰ,或在磷酸二酯酶和碱性磷酸酶处理下水解为精氨酸核糖基化血管紧张素-Ⅰ,然后对上述2种衍生物进行基于CID碎裂模式的串联质谱分析. 结果表明,与未衍生的精氨酸-ADP-核糖基化血管紧张素-Ⅰ相比,在鸟氨酸化血管紧张素-Ⅰ和精氨酸核糖基化血管紧张素-Ⅰ的质谱图上发现大部分来自于肽骨架碎裂的离子峰,可提供足够的序列信息以确定精氨酸-ADP-核糖基化位点.     

锌-精氨酸配合物极谱吸附波的研究

在乙醇胺 -盐酸溶液 ( p H9.5)中 ,锌 -精氨酸配合物在单扫示波极谱上于 -1 .2 7V( vs.SCE)产生灵敏吸附波。可用于 1 .0× 1 0 - 7～ 3 .0× 1 0 - 6 mol/L 范围内锌含量的测定 ,利用该波测定了人发和废水中锌的含量。该波为 1∶ 1锌 -精氨酸配合物在电极上吸附还原而产生。     

Application of arginine as an efficient eluent in cation exchange chromatographic purification of a PEGylated peptide

A cation exchange chromatographic purification process step was developed for the purification of human PEGylated PYY 3–36 from the PEGylation reaction mixture. In this publication we describe experiments carried out to evaluate the chromatographic performance of arginine chloride as an effective cation exchange chromatography eluent. Using arginine we obtained improved recovery and resolution during chromatographic purification of a peptide PEGylation reaction mixture. The chromatographic elution performance of arginine was compared to other cationic amino acids and sodium chloride. Arginine provided higher yield and better resolution of product from other process impurities. The process was successfully scaled up to produce clinical supplies. The basis for improvement in process performance with arginine was characterized by examining the effect of buffer and concentration of the PEGylated peptide on hydrodynamic volume of the molecule in solution. These results were used to predict the behavior of the molecule in the chromatography process. The enhanced chromatographic performance could be attributed to changes in molecular size with concentration, higher eluent strength of arginine, and resulting changes in mass transfer resistance.     

An in silico analysis of primary and secondary structure specificity determinants for human peptidylarginine deiminase types 2 and 4

Human peptidylarginine deiminases (hPADs) are a family of five calcium-dependent enzymes that facilitate citrullination, which is the post-translational modification of peptidyl arginine to peptidyl citrulline. The isozymes hPAD2 and hPAD4 have been implicated in the development and progression of several autoimmune diseases, including rheumatoid arthritis and multiple sclerosis. To better characterize the primary and secondary structure determinants of citrullination specificity, we mined the literature for protein sequences susceptible to citrullination by hPAD2 or hPAD4. First, protein secondary structure classification (α-helix, β-sheet, or coil) was predicted using the PSIPRED software. Next, we used motif-x and pLogo to extract and visualize statistically significant motifs within each data set. Within the data sets of peptides predicted to lie in coil regions, both hPAD2 and hPAD4 appear to favor citrullination of glycine-containing motifs, while distinct hydrophobic motifs were identified for hPAD2 citrullination sites predicted to reside within α-helical and β-sheet regions. Additionally, we identified potential substrate overlap between coil region citrullination and arginine methylation. Together, these results confirm the importance and offer some insight into the role of secondary structure elements for citrullination specificity, and provide biological context for the existing hPAD specificity and arginine post-translational modification literature.