2,4—二硝基氟苯柱前衍生法测定氨基酸的改进

本文报道了用２,４－二硝基氟苯柱前衍生反相高效液相色谱法测定氨基酸,１５种常见的氨基酸可得到很好的分离。衍生物很稳定,在室温下保存两个月无明显变化,检测极限可达到５ｐｍｏｌ。本法可应用于食品,药品等样品的氨基酸测定。     

青枯病生防菌ANTI-8098A菌株发酵过程氨基酸变化动态的研究

青枯病生防菌ANTI- 80 98A发酵过程的氨基酸测定结果表明 :ANTI - 80 98A的氨基酸代谢消耗发生在 0～ 2 4h ,消耗了 87.0 7%的总氨基酸 ;代谢累积发生在 2 4～ 4 8h ,4 8h的总氨基酸为 0h的 1 .6 7倍。在 1 7种测定的氨基酸中 ,1 6种氨基酸都表现出与总氨基酸类似的变化趋势 ,丝氨酸在 32h有最大值 ;根据含量大小可分为 3类 ,根据变异系数大小也可分为 3类 ,其中谷氨酸含量 ,丝氨酸变异系数最大。氨基酸种类特性的聚类分析结果表明 :当λ =1 7.5 0时 ,氨基酸变化可分为 4大类。发酵时间的聚类分析结果表明 :当λ=2 5 .36时 ,可分为 3大类 ,与总氨基酸的变化相关     

崂山绿茶叶中主要游离氨基酸的组分及含量分析

目的：探析崂山绿茶叶中主要游离氨基酸的组分及含量。方法：依据《茶水浸出物测定》相关标准,采用水浸提法予以完成,采用AccQ·Tag方法对崂山绿茶茶叶当中的氨基酸进行分析。结果：应用崂山绿茶叶茶水样品处理所获得的在具体的游离氨基酸总量与传统相比提升28.6%,在4种茶叶当中主要氨基酸含量呈现出同步增加的状况,所选取的所有经过检测的氨基酸在具体含量上均存在不同程度增加,并且在含量排序方面也基本存在一致性。结论：与直接测定茶汤中的氨基酸相比,崂山绿茶叶茶水样品制备处理虽然操作上较为繁琐,但更能准确反映茶叶中游离氨基酸的含量。因此,可采用茶水样品制备对茶汤直接测定予以代替,使其作为茶水游离氨基酸测定的前处理方法,更能够准确反映崂山绿茶叶中主要游离氨基酸的含量。     

异硫氢酸苯酯法(PITC)分析氨基酸

<正> 自从1958年Moore等人建立氨基酸测定方法以来,氨基酸分析方法发展迅速,日新月异。除采用阳离子交换柱,茚三酮柱后反应测定氨基酸方法外,70年代起,各种采用柱前衍生,反相色谱法分离测定氨基酸方法相继问世,为氨基酸分析开辟了新的领域。异硫氢酸苯酯(PITC)法作为其中一种,以其灵敏度高(可检测,1Pmal),分析速度快(水解液为10分钟,生理体液40～60分     

改进AccQ.Tag法快速测定9R复合氨基酸和3H支链氨基酸注射液中氨基酸含量

应用改进的 A cc Q.Tag法测定 9R复合氨基酸注射液和 3H支链氨基酸注射液中氨基酸含量 ,仅用 9m in就可快速分离测定。经与标准 Acc Q .Tag法测定结果比较 ,该法准确、快速 ,具有很好的实用性     

油茶籽氨基酸成分分析

油茶籽醇提物经阳离子交换树脂分离;水提物经酸水解,双向纸层析分离;用氨基酸分析仪测定,油茶籽含有十五种游离氨基酸和八种水解蛋白质氨基酸,对动物由入氯化碳引起肝损伤,有促进恢复的作用,无毒性,可利用的药源丰富。     

海南产螺旋藻粉蛋白质氨基酸

采用Tecator自动定氮仪和Waters PICO-TAG氨基酸自动分析仪测定了海南螺旋藻粉中蛋白质含量和17种氨基酸含量。结果显示海南螺旋藻粉中蛋白质含量达63.3%,总氨基酸含量达60.88%,其中必需氨基酸含量超过40%,比例平衡,符合FA0标准,可与国外产品媲美。     

人血清中游离色氨酸、苯丙氨酸和酪氨酸的微量测定——附我国健康成人测定值报告

测定人血清中游离氨基酸、特别是某些特殊氨基酸含量的变化,作为研究蛋白质代谢的指标,在临床医学研究方面已有很多报道。目前从测定生物体液和组织中,个别或某些氨基酸浓度的变化,已能诊断六十余种先天性氨基酸代谢缺陷的疾病,从而指导治疗。如患苯酮尿症的婴儿,血清中游离苯丙氨酸浓度可高出常人数倍,游离酪氨酸浓度则减低,如能在出生后短期内作出诊断并限制食物中苯丙氨酸含量,     

商品鹿鞭中氨基酸含量比较

采用氨基酸自动分析仪测定不同品种与产地的9份鹿鞭药材中氨基酸成分的种类及含量。这9份样品中均含17种氨基酸,其中人体必需氨基酸6种。17种氨基酸中以甘氨酸含量最高,必需氨基酸中亮氨酸含量最高;比较不同样品的含量,以辽宁西丰的梅花鹿鞭的总氨基酸含量最高,黑龙江梅花鹿鞭的必需氨基酸含量最高。结论为不同产地鹿鞭中氨基酸含量有一定差异,该方法可用于鹿鞭药材的质量评价。     

20例健康成人血清中游离氨基酸的分析比较

使用Beckman 119CL 氨基酸分析仪生理柱方法对20例健康成人血清中游离氨基酸作了分析测定:所得结果与Dickinson 等人实验结果进行了比较,从而确定了健康成人血清中游离氨基酸的正常参考值,这些数据可对于先天性氨基酸代谢紊乱、慢性肝炎、中枢神经系统等疾病治疗和临床诊断提供参考。     

高效液相色谱法分析虾头中的氨基酸

采用OPA柱前衍生氨基酸,用高效液相色谱法,经多步洗脱,用荧光检测器检测,分析虾头中各类氨基酸。用时短,样品用量少,灵敏度高,适用于分析大量样品     

Effects of Single Mutations on Protein Stability Are Gaussian Distributed

The distribution of protein stability effects is known to be well approximated by a Gaussian distribution from previous empirical fits. Starting from first-principles statistical mechanics, we more rigorously motivate this empirical observation by deriving per-residue-position protein stability effects to be Gaussian. Our derivation requires the number of amino acids to be large, which is satisfied by the standard set of 20 amino acids found in nature. No assumption is needed on the number of residues in close proximity in space, in contrast to previous applications of the central limit theorem to protein energetics. We support our derivation results with computational and experimental data on mutant protein stabilities across all types of protein residues.     

高效液相色谱测定蕨类植物中氨基酸含量

以5种蕨类植物(大羽贯众、美丽复叶耳蕨、黄山鳞毛蕨、狗脊蕨和紫萁)根状茎为研究材料,利用邻苯二甲醛柱前衍生高效液相色谱法分析了材料中的氨基酸成分.鉴于材料中蛋白质含量较低,测定方法中增加了样品的使用量并采用了梯度洗脱程序.结果表明,测试的5种蕨类植物所含总氨基酸含量较低,很少有超过5%,尤其在狗脊蕨中只有1.74%.在...     

Automated fluorometric amino acid analysis: the determination of proline and hydroxyproline.

A fluorometric method for the automated determination of the imino acids proline and hydroxyproline has been developed. The assay is based on the postcolumn reaction of the imino acids with alkaline sodium hypochlorite, which yields oxidation products amenable to detection with fluorogenic amine reagents. The method is simple and can be adapted readily to high-sensitivity amino acid analyzers which use o-phthalaldehyde for detection. As little as 10 pmol proline and 20 pmol hydroxyproline can be determined accurately. Thus the full array of natural imino and amino acids can now be determined on a high-sensitivity amino acid analyzer using o-phthalaldehyde.     

A Simple Gasometric Method for Determination of Free Amino Acid Contents in Biological Fluids

A simple method for the determination of total amino acid contents in biological fluids which contain various amino acids, peptides and proteins is described. This method is based on the determination in a Gilson differential respirometer of CO₂ gas evolved by the reaction of chloramin-T with α-amino-carboxylic acids in 5% trichloroacetic acid. The use of the trichloroacetic acid greatly suppressed interference by amines and ammonia, thus making this method appreciable to the determination of free amino acids in biological fluids without prior separation. Samples containing 1~20 μmoles of free amino acids can be assayed with accuracy of ±3%. This method was applied to the study of proteolytic digestion of casein.     

Isolation and quantitation of isotopically labeled amino acids from biological samples

To face the problem of simultaneous isolation and quantitation of isotopically labeled amino acids in biological samples, two semi-preparative chromatographic methods were developed. One method was especially designed to isolate radioactively labeled amino acids for which we used derivatization with the fluorophore o-phtaaldialdehyde (OPA), which is known to be easy and reliable. Isolation of amino acids labeled with stable isotopes required another approach as we wanted to use isotope ratio mass spectroscopy (IRMS), which can only be performed on pure, non-derivatized amino acids. Becuase the OPA probe cannot be removed after isolation of the derivative, we used 9-fluorenylmethylchloroformate (FMOC) instead. This probe is linked to an amino acid via a peptide bond which can easily be broken byb gas-phase acid hydrolysis (103% recovery after 5 h at 150°C: S.D = 3.5%, n = 14). Run time (injection to injection) was 60 min for the OPA method and 75 min for the FMOC method. Both fluorescence and UV absorbance detection can be employed. The coefficient of variation (C.V.) for peak area measurement was below 2% for most OPA amino acids and below 3% for most FMOC amino acids. At maximum, a total of 1000 μl could be injcted, representing approximately 200 μl of deproteinized plasma. The methods were linear up to injection of 0.5 μmol of all amino acids (OPA: r²=0.995−0.999; FMOC: r²=0.992−0.999). The C.V. of the IRMS measurement within the range which can be isolated maximally in one chromatographic run (50–500 nmol), was less than 3% above 100 mmol, indicating that chromatographic isolation fulfils the needs of the IRMS determination. The resulting methods are suitable for the isolation and quantitation of micromolar amounts of labeled amino acids from biological samples.     

中华鳖氨基酸和微量元素的分析与研究

本文对中华鳖的氨基酸、维生素、微量元素等营养物质进行了分析，并与其它十种水产品进行了比较，通过对中华鳖的化学分（ＣＳ）、氨基酸分（ＡＳ）和必需氨基酸指数（ＥＡＡＩ）的计算可知，中华鳖的微量元素构成较为合理，氨基酸构成与ＦＡＯ模式近似。     

Fluorometric assay of secondary amino acids

A method is described for the conversion of secondary amino acids to primary amines which can be assayed with fluorescamine (I). Secondary amino acids undergo oxidative decar?ylation when reacted with halogenating agents. The resulting imines are hydrolyzed to primary amines, which are subsequently allowed to react with fluorescamine (I) to yield fluorescent pyrrolinones (II). This reaction sequence provides an efficient fluorometric assay for secondary amino acids. Thus, the fluorescamine procedure is now applicable to the full array of natural amino acids.     

New approach for amino acid profiling in human plasma by selective fluorescence derivatization

A new approach for the separation of 6-aminoquinolyl-carbamyl (AQC)-derivatized amino acids has been proposed. The chromatography used ion-pairing mechanism to increase the method selectivity. Mobile phase was based on triethylamine buffer containing N,N-dimethyloctylamine as a modifier. A number of factors, buffer composition and pH, counterion concentration, temperature and acetonitrile gradient profile, were optimized to achieve final chromatographic conditions. With the presented analytical method, the separation and identification of 34 AQC-amino acids and amino compounds present in human plasma is possible. The results of validation proved the applicability of the method for quantification of 27 amino acids in biological samples. The ultrafiltration proposed as deproteinization procedure gave repeatable and reliable results for the amino acids under investigation. This method introduced in routine testing can be a suitable tool for amino acid profiling in plasma including all aspects of clinical application.     

Simultaneous analysis of enantiomeric composition of amino acids and N-acetyl-amino acids by enantioselective chromatography

Among the three chiral columns, CHIROBIOTIC T, CHIRLPAK WH, and CHIRALCEL OD-R, tested for the separation of racemic amino acids and N-acetyl-amino acids, only CHIROBIOTIC T chiral column which is based on covalently bonded amphoteric glycopeptide, teicoplanin, as the stationary phase ligand could be successfully developed to enantiomerically separate racemic amino acids and N-acetyl amino acids simultaneously. This method can be used to determine the enantiomeric composition of amino acids and N-acetyl-amino acids in the catalysis of D-aminoacylase or L-aminoacylase and the conversion rate of N-acylamino acid racemases.