K系数－多波长最小—乘回归分光光度法同时测定三组分的研究

将双波长Ｋ系数分光光度法和多波长线性回归分光光度法相结合，并采用最小一乘法准则计算回归系数，提出了一种同时测定三组分的新方法，即Ｋ系数－多波长最小一乘回归分光光度法。该法不需要吸收曲线交点和等吸收点，且能较好地克服异常点的影响，得到比最小二乘法更好的回归稳健性。方法用于测定模拟混合色素样品和饮料样品中的柠檬黄、胭脂红、果绿，相对误差为—３．６％～２．８％，回收率为９６．３％～１０４．８％，变异系数小于２．７９％。     

甲胺分子多光子电离质谱研究

胜多光子电离飞行时间质谱法，利用可调谐脉冲激光器，测得了甲胺分子在不同激光波长和激光功率下的多光子电离和解离产物。母体离子ＣＨ３ＮＨ＾＋２的离解速常数随激光发波长的增大而减小。     

正交投影用于多波长色谱重叠峰分析

 将正交投影分辨 (OPR)技术用于多波长色谱重叠峰分辨 ,当色谱峰中最大重叠度小于或等于波长数时 ,用这一方法能从多波长色谱重叠峰中获得完全真解。基于双波长色谱分析 ,提出了一种新的色谱重叠峰中背景校正、组分数和纯组分信号区确定以及各组分重叠情况的分析方法 ,即双波长特征信息分析 (DWCI)。该法被成功的用于三组分双峰和双组分单峰重叠色谱的分析。     

比值导数波谱-多波长最小一乘回归分光光度法同时测定饮料中糖精钠、苯甲酸和山梨酸

提出了比值导数波谱－多波长最小一乘回归分光光度法。该法能同时测定三组分混合物而毋需零交点波长和等吸收点，且回归稳健性好．可消除异常点的影响。方法用于合成样品和饮料中糖精钠、苯甲酸和山梨酸的同时测定，相对误差＜± ３． ５％，回收率为 ９６． ６％～１０４．４％，相对标准偏差为２．０％～３．１％．     

荧光法测定Fenton反应产生的羟自由基

建立了一种新的测定Ｆｅｎｔｏｎ反应产生羟自由基·ＯＨ的方法。Ｃｅ＾３＋在稀硫酸中能产生特征荧光，其最大激发波长和发射波长分别为２８０ｎｍ和３６０ｎｍ。Ｆｅｎｔｏｎ反应产生的·ＯＨ能将Ｃｅ＾３＋氧化成Ｃｅ＾４＋，用荧光法测定Ｃｅ＾３＋的荧光强度变化即可间接测定羟自由基的产生量。通过对测定条件的研究，得到最佳实验条件，。结果表明，该方法稳定性好、操作简便、测定快速，可作为一种简便的筛选抗氧化剂的方法。     

三波长分光光度法研究：Ⅲ.两测量波长法提高测定灵敏度

本实验利用两测量波长法提高三波长光光度法的灵敏度，选择合适的波长组合，消除两种共存组分的干扰，使△Ａ＝Ａλ１＋Ａλ２－ＫＡλ３只与待测组分的浓度有关，灵敏度一般均高于单波长法。以相对误差为选择波长组合的标准，编制了程序，用计算机选择合适的波长组合，验证结果令人满意。     

VitaminK脉冲辐解与激光光解的研究（Ⅰ）——VK3水溶液脉…

研究了ＶＫ３水溶液经脉冲辐射后ＶＫ３阴离子自由基的形成机理及其次级反应，观察到ＶＫ３阴离子自由基的最大吸收波长位于约３４０ｎｍ处，这与ＶＫ３阴离子自由基最大吸收波长大３９０ｎｍ附近的观点有所不同，并初步分析了这种差异的原因。初步探讨了ＶＫ３对Ｔｈｙｍｉｎｅ＾－１和Ａｄｅｉｎｅ＾－的修复作用，显示ＶＫ３本身是很好的辐射保护剂。     

简讯

双波长标准加入吸光光度法同时测定锌汞国防科技大学研究了一种利用化学计量学原理改善分析方法选择性的计算分析方法——双波长标准加入吸光光度法(简称双标法)。双波长吸光光度法用于多组分相互干扰体系的测定,主要有等吸收点法和系数倍率法等。这两种方法通常是测量信号下降以消除共存物干扰,改善选择性,但在一定程度上     

K系数—多波长最小一乘回归分光光度法同时测定三组分的研究

将双波长Ｋ系分光光度法和多波长线性回归分光光度法相结合，并采用最小一乘法准则计算回归系数，提出了一种同时测定三组分的新方法，即Ｋ系数－多波长最小一乘回归分光光度法。     

石墨炉原子吸收光谱法中氯化铒和硝酸铒的背景吸收特性研究

研究了石墨炉原子吸收光谱法中ＥｒＣｌ３、Ｅｒ（ＮＯ３）３基体的背景吸收影响。背景吸收波长特性的研究说明，ＥｒＣｌ３与Ｅｒ（ＮＯ３）３的背景吸收都具有明显的波长特性。将铒基体转化为Ｅｒ（ＮＯ３）３有利于降低背景吸收值。ＥｒＣｌ３背景吸收的时间特性和原子化温度与原子化方式有关。铒基体的背景吸收峰高与灰化温度有关。     

RELATIVE CONTRIBUTIONS OF TRYPTOPHAN and TYROSINE TO THE PHOSPHORESCENCE EMISSION OF HUMAN SERUM ALBUMIN AT LOW TEMPERATURES

Abstract— Phosphorescence emission and excitation spectra, as well as decay profiles of human serum albumin, were investigated in the wavelength regions of the tryptophan and tyrosine absorption and emission spectra in potassium phosphate buffer at 77 K. Emission and excitation spectra were found to be linear superpositions of the contributions of the tryptophan and tyrosine residues. It is suggested, therefore, that there is no significant tyrosine to tryptophan energy transfer in this protein at low temperature. The phosphorescence decay is, in general, multiexponential with lifetime components of 5.95, 2.7, and 1.2 s. The longest lifetime is characteristic of tryptophan, whereas the two short components are attributed to two types of tyrosine residues located in different environments within the protein. The latter is confirmed by a detailed analysis of the phosphorescence decay profiles determined at different emission wavelengths, and utilizing different wavelengths of excitation favoring either the tryptophan or tyrosine residues.     

萘及其衍生物荧光光谱的计算解析及同时测定

本文研究了pH12条件下, 萘、1-萘酚和2-萘酚的荧光、一阶导数荧光、同步荧光和一阶导数-同步荧光光谱。根据各谱性质, 结合多波长线性回归、双峰倍增配平和峰值系数等不同计算手段, 建立了6种新的同时测定混合物中萘、1-萘酚和2-萘酚的荧光分析方法。     

Selective determination of tryptophan by using a carbon paste electrode modified with an overoxidized polypyrrole film.

We report on the selective determination of tryptophan, using a carbon paste electrode coated with an overoxidized polypyrrole film. Out of 21 protein amino acids, only tryptophan and tyrosine exhibited an oxidative voltammetric response with this electrode. Tryptophan, which was preferentially concentrated to the electrode under an open circuit condition, was determined by the stripping voltammetric technique with a linear response range of 10-100 microM. For the determination of 10 microM tryptophan, interference from a 15-fold excess of tyrosine gave an positive error of 6%, while the other amino acids did not exhibit any detectable interference.     

Dual Signals Electrochemical Biosensor for Point-of-Care Testing of Amino Acids Enantiomers

A highly sensitive electrochemical sensor based on both potential and current dual signals was constructed via polypyrrole-coated chiral carbon nanotubes (L/D-CNT@PPy) loaded with Pt nanoparticles (Pt NPs) and β-cyclodextrin (β-CD) hybrid. Using L/D-CNT and β-CD as chiral selectors, PPy and Pt NPs enhanced the conductivity and the sensors showed excellent performance for chiral recognition of tyrosine (Tyr) and tryptophan (Trp). The linear ranges of the D-CNT@PPy@Pt NPs@β-CD sensor were 3–30 μM (Tyr) and 19.6–196 μM (Trp), respectively, the detection limits were 0.107 nM (Tyr) and 0.133 nM (Trp), respectively, and the recoveries for L-Tyr were 96.56 %–106.32 %. This electrochemical sensor based on a dual-signal strategy of potential and current was expected to be used in the field of point of care testing (POCT).     

LIGHT-INDUCED CHANGE IN RHODOPSIN EMISSION: PHOSPHORESCENCE and FLUORESCENCE

Abstract— Phosphorescence measurements of rhodopsin in bovine rod disk membranes were made to study changes in protein conformation on bleaching by probing the environment of tryptophan and tyrosine residues of the protein. Bleaching decreased the tyrosine phosphorescence by about 25% and significantly affected the amplitude of triplet decay when rhodopsin was excited at 280 nm, where both tyrosine and tryptophan absorb. Computer analysis using one or two exponential model functions showed the presence of two components in the decay curve at 410 nm—one with a lifetime of 2.2 s, the other with a lifetime of 4.8 s>—which are typical of tyrosine and tryptophan respectively. When the rod outer segment sample was bleached, there was a significant decrease in the amplitude of the tyrosine component. However, the lifetime values of the two components did not change. Analyses of the fluorescence spectra of dark and bleached membranes at different excitation wavelengths and the phosphorescence change on bleaching suggest energy transfer between tyrosine and tryptophan singlet states, which may result from a conformational change of the opsin moiety on bleaching.     

酪氨酸与色氨酸间电子转移——氧化还原活性及电子跃迁能的从头算研究

在HF/6-31G和GASSCF/6-31G水平上对色氨酸和酪氨酸间的电子转移进行了理论 研究。用类导体屏蔽模型考察体系的溶剂效应。通过对给、受体几何构型的优化, 计算了孤立的给、受体之间电子转移反应的内重组能和反应能差。分别用 Koopmans定理和CASSCF/6-31G方法计算了色氨酸和酪氨酸的电离能。计算了此两种 氨基酸从基态到最低激发态的跃迁能。理论计算结果很好地解释了N_3~·高选择性 地氧化色氨酸残基,并诱发电子从酪氨酸残基向色氨酸残基转移的实验现象。     

Syntheses of Atypically Fluorinated Peptidyl Macrocycles through Sequential Vinylic Substitutions

Small peptides containing combinations of cysteine, tyrosine, histidine, and serine residues react with octafluorocyclopentene (OFCP) to afford atypically structured macrocycles through successive vinylic substitutions. The reactions proceed rapidly in air at 0 °C and are tolerant of spectating tryptophan, asparagine, glutamine, and threonine residues. Hexapeptides of consensus sequence YXCXXC displace four fluorine atoms from OFCP to generate fluorinated macrobicyclic compounds that display dual‐turn surfaces. The method provides facile access to a wide range of previously unknown heterocyclic structures.     

Influence of energy transfer on the photoionization of tryptophan and tyrosine in basic media

Abstract— The luminescence studies of the delayed isothermal and light stimulated recombinations of photoejected electrons with photoionized chromophores at 77°K show that in the peptide tryptophyltyrosine, where energy transfer occurs at the singlet level from tryptophan to tyrosine and at the triplet level from tyrosine to tryptophan, tryptophan photoionization is greatly enhanced. This increase in photoionization efficiency is attributed to triplet-triplet transfer.     

Connecting Tyrosine and Tryptophan Units of Diazonamide A and Azonazine by a Diastereodivergent Arylative Dearomatization

We report the Friedel–Crafts coupling of a tyrosine unit with tryptophan‐derived pyrrolindolenium ions which are configurationally stable. The reaction allowed the stereoselective and divergent access to the required quaternary stereocenters found in diazonamide A and azonazine at the junction of the tyrosine and tryptophan units.     

Electrochemical investigations of amino acids at solid electrodes: Part II. Amino acids containing no sulfur atoms: Tryptophan,tyrosine, histidine and derivatives

The electrochemical properties of amino acids containing no sulfur atoms have been investigated using stationary or rotating solid electrodes such as Au and vitreous carbon. Among the 20 amino acids present in the proteins only tryptophan and tyrosine are specifically oxidizable at a gold, platinum or carbon electrode. Histidine is oxidizable only at a carbon electrode. In the case of tryptophan and tyrosine the oxidation phenomena are very similar whatever the nature of the electrode. Oxidation can be performed on a smooth surface electrode, and at the level of metal oxide formation it leads to a mixture of monomeric species (oxindolalanyl with tryptophan and hexacyclodienone alanyl with tyrosine) and polymeric species (filming effect: polytryptophan with tryptophan, polyphenylene oxide alanyl with tyrosine). According to experimental features (pH, concentrations, electrode angular velocity, etc.) either the first of the second electrochemical oxidation pathway can be favored.