Inhibitory Effect of Amino Acids and Dipeptides on the Sensitized Photooxidation of Fats

The protective effect of amino acids and dipeptides on the singlet molecular oxygen photo-oxidation of soybean oil and thier FAME was investigated, in homogeneous media and in aqueous emulsions. Soybean oil was chosen as an example of fat due to its particular stability problem. In the presence of 10–100 ppm of the amino acids, photo-oxidation of the fats in relatively concentrated solutions, was considerably retarded when exposed to visible light, with an added sensitizer. The study indicates that amino acids and peptides, could acd as protective agents against fats photo-oxidation, specially in foods containing oxidizable non saturated fatty acids, constituted in many cases by emulsions, where fats can simultaneously be disolved with proteineaceous compounds.     

Effect of Amino Acids on Micellization,Surface Activity and Micellar Properties of Nonionic Surfactant Hexadecyl Alcohol Ethoxylate (25EO) in Aqueous Solutions

The effects of amino acids (dl ‐glycine, dl ‐alanine, dl ‐phenylalanine, dl ‐serine, l ‐leucine, l ‐aspartic acid, l ‐lysine) on the micellization, surface activity, viscometric and aggregation properties of hexadecyl alcohol polyethoxylate (25EO) in aqueous solution were studied. The critical micelle concentration and free energy of micellization were evaluated and discussed. The surface excess concentration, the minimum area per molecule, the surface pressure at the critical micelle concentration and the standard free energy of adsorption were obtained from surface activity studies. On the basis of the determination of the relative viscosities on concentration, the viscosity B‐coefficients of the Jones–Dole semiempirical equation were calculated for the premicellar and postmicellar regions. The method of fluorescence quenching was used for determination of the micellar aggregation number of hexadecyl alcohol polyethoxylate (25EO) in aqueous solution in the presence of amino acids. It was found that among studied amino acids serine shows behavior that is different from that of the other neutral amino acids.     

蛋清合成复合氨基酸锌的研究

氨基酸锌作为新一代微量添加剂在医药、食料行业广泛应用。通过采用新型工艺选用鸡蛋清为原料,通过水解得到复合氨基酸,再与ZnO反应生成复合氨基酸锌。通过对氨基酸锌合成工艺的研究,讨论了蛋清水解时间与温度等因素对于产品产量的影响,水解以温度30℃,水解3 h以内为宜,pH控制在5~7较为合适。     

制备型氨基酸离子交换色谱的动态特性

为描述氨基酸离子交换色谱的动态过程，考虑传质机理，非线性离子交换平衡关系以及各种形式的进料函数，提出了色谱的机理模型及其数值解法，理论预测的洗脱峰与实验现象比较吻合，证明该理论模型可以指导氨基酸离子交换色谱的优化和设计。     

Studies on the Effect of Amino Acids/Peptide on Micellization of SDS at Different Temperatures

Conductivities of (0.001–0.012) m sodium dodecyl sulfate have been determined in water and in the presence of 0.10 m aqueous glycine/alanine/glycylglycine at 298.15, 303.15, 308.15, and 313.15 K. From the specific conductivity data, the critical micellar concentration, degree of counter ion association, degree of counterion dissociation, free energy of transfer of hydrophobic chain from the medium to interior of the micelle, and surface contribution, standard free energy of micellization, standard enthalpy of micellization, and standard entropy of micellization of sodium dodecyl sulfate have been computed. The thermodynamic parameters of micellization and the effect of additives on these parameters have been used to study the interactions present in the micellar systems.     

氨基G酸及2—萘胺—3,6,8—三磺酸的合成研究

本文以Ｇ盐为原料,经加氨化反应合成了氨基Ｇ酸,并以氨基Ｇ酸为原料,经发烟硫酸磺化反应合成了２－萘胺－３,６,８－三磺酸,并对影响反应的因素做了探讨。研究表明,随反应温度、反应时间、氨水浓度、氨比、催化剂用量的提高,氨基Ｇ酸收率增大。用４０％￣６０％发烟硫酸,反应温度为１３０℃,氨基Ｇ酸／ＳＯ３＝１：７．５￣１：８．５时,２－萘胺－３,６,８－三磺酸产品收率约为９０％。     

溴化十六烷基吡啶在HCl中对冷轧钢的缓蚀作用

用失重法研究了在1.0 mol/L HCl中20~50℃时溴化十六烷基吡啶(HDPB)在冷轧钢表面上的吸附及缓蚀作用。结果表明,HDPB对钢具有良好的缓蚀作用,缓蚀率随缓蚀剂浓度和温度的增加而增大;HDPB在钢表面的吸附符合Langmuir吸附模型。求出了相应的吸附热力学参数(吸附自由能ΔG0,吸附焓ΔH0,吸附熵ΔS0),并根据这些参数详细讨论了缓蚀作用机理。     

Effect of Benzheterazoles on the Micellar Behavior of Sodium Dodecylsulfate in Dimethylsulfoxide: A Conductometric and Spectroscopic Approach

In this article, we report intermolecular interactions in terms of the effect of benzfused heterocyclic compounds, i.e., 2-thioureidobenzimidazole and 2-thioureidobenzoxazole (0.00, 0.01, and 0.05 mol kg⁻¹), on the micellization behavior of sodium dodecylsulphate (SDS) (1–52 mmol kg⁻¹) in dimethylsulphoxide (DMSO) at different temperatures (293.15–313.15 K) through conductometric and spectroscopic investigations. The variation of specific conductance with SDS concentration has been utilized to estimate the critical micelle concentration ( CMC). The above-performed techniques infer that the presence of additives results in a decrease in the CMC values. Various standard thermodynamic parameters such as free energy change (), enthalpy change (), and entropy change () of micellization have been determined using the temperature dependence of CMC. The above calculated parameters and also UV–visible and fluorescence spectroscopy have been used to obtain information regarding the various interactions between the compounds and surfactant aggregates. In addition, an attempt has also been made to examine the minimum inhibitory concentration (MIC) of the heterocompounds, which indicates the effectiveness of these compounds against fungus growth at a particular concentration. These synthetic heterocyclic compounds find increasing applications in material science, medicinal chemistry, and biochemistry due to their antifungal and antioxidant properties.     

A Comparative Study on the Aggregation and Thermodynamic Properties of Anionic Sodium Dodecylsulphate and Cationic Cetyltrimethylammonium Bromide in Aqueous Medium: Effect of the Co-solvent N-Methylacetamide

The effect of co‐solvent N‐methylacetamide (NMA) (0.035, 0.046, 0.127, and 0.258 mol kg^?1) on the micellization behaviour of anionic surfactant sodium dodecylsulphate (SDS) (3.21–10.35 mmol kg^?1) and cationic surfactant cetyltrimethylammonium bromide (CTAB) (0.19–3.72 mmol kg^?1) in aqueous solution was explored by employing conductivity measurements at different temperatures (298.15–313.15 K). The critical micelle concentration (CMC) values for SDS and CTAB in aqueous solutions of NMA were determined from the conductivity versus surfactant concentration plots. The variations in the CMC values of SDS with NMA concentration are in striking contrast to those observed in the case of CTAB. The various relevant thermodynamic parameters of micellization, viz. standard enthalpy change, ΔH_m^o, standard entropy change, ΔS_m^o, and standard Gibbs free energy change, ΔG_m^o, were determined using the temperature variation of the CMC values and counterion binding. The results not only relate these thermodynamic parameters to the consequences of intermolecular interactions but are also able to differentiate between SDS–water–NMA and CTAB–water–NMA systems in terms of contributions from head groups as well as alkyl chains of surfactants.     

Role of Amino Acids on In Situ Photografting of Jute Yarn with Acrylamide Using Ultraviolet Radiation

Abstract

To improve the mechanical performance of jute yarn, grafting with acrylamide (AM) monomer has been performed on in situ UV radiation and optimized; the monomer concentration (30%) and irradiation time (60 min) attained 195% tensile strength with 22% polymer loading (PL). The effect of amino acids (1%) as additives in AM with photografted jute yarn at optimized system has been studied. The PL and tensile properties, such as tensile strength (TS) and elongation at break (Eb), of treated samples were enhanced by incorporation of amino acids, and the highest TS value (270%) and Eb value (300%) with 27% PL value were achieved by the sample treated with L‐arginine (Arg). Weak acid [3% acetic acid (Ace)] and strong acid [1% sulfuric acid (Sul)] were also incorporated in the optimized system of AM grafting to investigate their effect on the mechanical properties of photografted jute yarn. Water absorption and weathering resistance of treated untreated samples (TS₀) were also studied.     

The Effect of Polar Head and Chain Length on the Physicochemical Properties of Micellization and Adsorption of Amino Alcohol-Based Surfactants

In this work, we have synthesized a series of quaternary ammonium from amino alcohols and n-bromoalkanes. The compounds are referred to as C_nEtOH, C_nPrOH, and C_niPrOH (where n = 12 and 14 carbons, EtOH = ethanol, PrOH = propanol, iPrOH = iso-propanol). Their structures were checked using the usual spectroscopic methods [¹H, ¹³C nuclear magnetic resonance (NMR) and infrared (IR)]. Their physicochemical properties in aqueous solution were studied using conductivity, surface tension, and ultra violet (UV)–visible absorption spectroscopy measurements. This study was conducted to show the effect of the linear hydrophobic chain and the location of the OH polar group with respect to the N⁺ quaternary ammonium on the physicochemical properties of the surfactants. The comparison between the physicochemical properties of the surfactants studied shows a distinct effect of the position of the OH group on the critical micelle concentration (CMC), the ionization degree (α), the area occupied at the interface (A_min), the free energy of adsorption (), and the free energy of micellization (). The intermolecular interaction between the synthetic surfactants and the methyl orange (OM) dye is related to the degree of hydration of the micelle, proven by the hypsochromic displacement of OM wavelength (λ_max) and ionization (α) of the micelles. The CMC, the degree of ionization, and the degree of hydration of the micelle follow the same trend.     

氨基酸的应用与发展趋势

介绍了氨基酸在食品,医药,添加剂及化妆品行业的应用,提出运用基因工程手段生产氨基酸是一种趋势,大力发展药用中间体是世界氨基酸工业的新潮流。     

松香基氨基噻二唑衍生物的合成及抑菌活性研究

以松香或歧化松香为起始原料,通过提纯、Diels-Alder双烯加成和关环等反应合成了4个新型松香基氨基噻二唑衍生物化合物。通过红外、MS、1HNMR和元素分析对产物进行表征和确认。采用最低抑菌浓度法对目标产物的抑菌性能进行了测试,初步的结果显示化合物都有一定的抑菌活性,特别是化合物5-脱氢枞基-2-氨基-1,3,4-噻二唑对金黄色葡萄球菌和表皮葡萄球菌具有良好的活性,对其最低抑菌浓度均为4μg/mL。     

氨基磺酸的生产及应用

论述了氨基磺酸的三种生产方法,并介绍了氨基磺酸的开发情况。     

Aggregation Behavior of Imidazolium-Based Amino Acid Ionic Liquid Surfactants in Aqueous Solution: The Effect of Amino Acid Counterions

Three kinds of imidazolium-based amino acid ionic liquid surfactants (AAILS), 1-tetradecyl-3-methylimidazolium _L-aminopropionic acid salt ([C₁₄mim][Ala]), 1-tetradecyl-3-methylimidazolium _L-2-pyrrolidinecarboxylic acid salt ([C₁₄mim][Pro]), and 1-tetradecyl-3-methylimidazolium _L-aminohydrocinnamic acid salt ([C₁₄mim][Phe]), were synthesized by employing natural amino acids as counterions. Their adsorption and self-aggregation behaviors in aqueous solution were investigated systematically by means of surface tension and electrical conductivity measurements. Surface tension results indicate that surface properties and micellization behavior of AAILS are significantly affected by counterions. The micellization of [C₁₄mim][Pro] and [C₁₄mim][Phe] is entropy-driven at low temperatures but enthalpy-driven at high temperatures, whereas [C₁₄mim][Ala] is enthalpy-driven throughout the whole temperature range, owing to the variation in hydrophobicity and size of amino acid counterions. The surface activity of [C₁₄mim][Phe] is superior to that of conventional imidazolium-based ionic liquid surfactants with the same hydrocarbon chain length, 1-tetradecyl-3-methylimidazolium bromide (C₁₄mimBr), indicating that the aromatic counterion can promote the micellar formation process.     

Synthesis and Use of Tetrahydrofuran‐ and Tetrahydropyran‐Amino Acids

Progress in the synthesis and the use of amino acids containing a THF or THP ring is reported. Different synthetic routes from carbohydrates or α‐amino acids as starting compounds are discussed. Examples for THF‐ and THP‐amino acids as peptidomimetics or building blocks for foldamers and combinatorial libraries are given. The role of THF‐amino acids in the synthesis of artificial ion channels, e.g. THF‐gramicidin hybrids, is highlighted.     

Oxidation of Amino Acids,Peptides and Proteins by Ozone: A Review

The kinetics and products of the reaction of ozone with specific amino acids, peptides, and proteins are reviewed based on studies reported in the literature. Ozone reacts mainly with the unprotonated amino group of the acids and the second-order ozone rate constants for these reactions, except for cysteine, methionine, and tryptophan, vary by about two-orders from 2.6?×?10⁴ to 4.4?×?10⁶ M^?1s^?1. The site of attack on cysteine and methionine by O₃ is at the sulfhydryl rather than the amino group to give sequential O-atom addition products. The order of reactivity for the oxidation of amino acids by O₃ at pH 8 is cysteine > tryptophan ≈ methionine > phenylalanine ≈ histidine > others, with half-lives mostly in the range of milliseconds to tens of seconds (1 mg L^-1 O₃ dose). Reactions of O₃ with aliphatic amino acids form nitrate, ammonia, and one or two carbon atom-containing carbonyl and carboxylic byproducts. In the ozonolysis of peptides and proteins, oxidation by O₃ occurs at the tyrosine, tryptophan, histidine, cysteine, and methionine residues. Oxidation of proteins results in changes in their folding ability and tertiary structures.     

氨基酸-银反应的光化学特点

氨基酸与银的反应是一个不借外加能量热力学上即可进行的过程,但当引入光之后,可改变反应速率.研究发现:Soret带出现吸收所需光照度的大小顺序为Asp Ag(I)>Thr Ag(I)>Tyr Ag(I)>Lys Ag(I),对于Cys Ag(I)体系,Cys的α羧基氧、α氨基的氮与银(I)结合时光照有利于反应的进行,而S原子与银(I)结合与光照度几无关系.此反应是光助化学反应.     

紫外光谱法对核黄素与金属离子及氨基酸络合的研究

采用紫外-可见光谱法在不同温度、相同的给体初始浓度、不同的体积配比下,通过测定吸光度从而确定了核黄素二元体系络合的规律及核黄素与金属离子和氨基酸络合的情况。温度分别为室温、25、30、37、40、45、50℃;给体与受体的体积比分别为1：1、2：1、3：1。     

Nuclear Magnetic Resonance Investigation of the Effect of pH on Micelle Formation by the Amino Acid‐Based Surfactant Undecyl l‐Phenylalaninate

Micelle formation by the anionic amino acid‐based surfactant undecyl l ‐phenylalaninate (und‐Phe) was investigated as a function of pH in solutions containing either Na⁺, l ‐arginine, l ‐lysine, or l ‐ornithine counterions. In each mixture, the surfactant's critical micelle concentration (CMC) was the lowest at low pH and increased as solutions became more basic. Below pH 9, surfactant solutions containing l ‐arginine and l ‐lysine had lower CMC than the corresponding solutions with Na⁺ counterions. Nuclear magnetic resonance (NMR) diffusometry and dynamic light scattering studies revealed that und‐Phe micelles with Na⁺ counterions had hydrodynamic radii of approximately 15 Å throughout the investigated pH range. Furthermore, l ‐arginine, l ‐lysine, and l ‐ornithine were found to bind most strongly to the micelles below pH 9 when the counterions were cationic. Above pH 9, the counterions became zwitterionic and dissociated from the micelle surface. In und‐Phe/l ‐arginine solution, counterion dissociation was accompanied by a decrease in the hydrodynamic radius of the micelle. However, in experiments with l ‐lysine and l ‐ornithine, micelle radii remained the same at low pH when counterions were bound and at high pH when they were not. This result suggested that l ‐arginine is attached perpendicular to the micelle surface through its guanidinium functional group with the remainder of the molecule extending into solution. Contrastingly, l ‐lysine and l ‐ornithine likely bind parallel to the micelle surface with their two amine functional groups interacting with different surfactant monomers. This model was consistent with the results from two‐dimensional ROESY (rotating frame Overhauser enhancement spectroscopy) NMR experiments. Two‐dimensional NMR also showed that in und‐Phe micelles, the aromatic rings on the phenylalanine headgroups were rotated toward the hydrocarbon core of micelle.