全自动氨基酸分析仪测定支链氨基酸粉中牛磺酸的含量

目的建立全自动氨基酸分析仪测定支链氨基酸粉中牛磺酸。方法样品经上样缓冲液(pH 2.2)溶解提取,按照氨基酸分析仪设定的钠体系程序洗脱,用Na型离子交换色谱柱分离,与茚三酮反应液在135℃下反应,生成可在570 nm和440 nm检测到的蓝色物质,采用外标法定量。结果牛磺酸在4.1065~20.5326μg/mL浓度范围内有良好的线性,r~2=0.999,回收率为101.28%,RSD为2.1%,检出限为15 mg/100 g。结论该方法准确可靠,不需要剧毒衍生试剂,适用于支链氨基酸粉中牛磺酸的测定。     

氨基酸的有效性对于蛋白消化率校正氨基酸评分的影响

蛋白质的传统化学评分是基于相关的氨基酸组成，蛋白消化率校正氨基酸评分综合了蛋白质的传统化学评分和氨基酸有效性的生物学评价。随着蛋白消化率校正氨基酸评分的产生，对于膳食蛋白品质的评价有了一个飞跃。本文重点研究测定蛋白中氨基酸有效性的问题，并讨了采用回肠消化率，粪便消化率，真消化率，实际消化率对于评价蛋白品质的不同影响。     

Competitive amino acid transport between L-tryptophan and other amino acids in Schizophyllum commune

In our study on nutritional requirement for the hyphal growth of Schizophyllum commune, we found that a Trp- mutant could not grow in the L-Trp-supplied medium in the presence of L-Ser. Further growth studies showed that not only L-Ser but also as many as 11 kinds of amino acid including L-Ala, L-Arg, L-Asn, L-His, L-Leu, L-Met, L-Phe, L-Ser, L-Thr, L-Tyr and L-Val inhibited the growth of the Trp- mutant in the L-Trp-supplied medium. However, these amino acids did not inhibit the growth of a Trp+ strain. The inhibition of growth of Trp+ strain induced by a Trp analogue of 5-fluoro-DL-tryptophan (5FT), which was usually recovered by L-Trp, was rescued by the same amino acids mentioned above. The exceptions were Gly and L-Ile, which also recovered the growth inhibition induced by 5FT. These results indicate that the permease responsible for the Trp transport in S. commune might also be active to other amino acids. However, it is considered that the permease shows high affinity to L-Trp and low affinity to other amino acids. As a result, the transport of L-Trp and 5FT may be counteracted by other amino acids.     

直接氨基酸法测定乳清粉中氨基酸

本文通过使用氨基酸直接分析法——离子交换色谱-积分脉冲安培法（HPIC—IPAD）对乳清中游离的氨基酸和水解后乳清粉中的氨基酸进行检测分析。结果表明，可以检测到孔清粉中含有游离氨基酸6种，水解以后可以检测到15种氨基酸．而且氨基酸的保留时间（Rt）相对标准偏差（RSD）平均为1．843％，峰面积RSD平均为2．6174％。     

酿造酱油中特征氨基酸含量检测及对氨基酸态氮贡献的分析

为分析酿造酱油特征氨基酸组成及对氨基酸态氮的贡献,比较了3款不同类型样品中的游离氨基酸含量和氨基酸态氮组成。结果表明,酿造酱油中氨基酸种类丰富,无增鲜剂添加的样品中氨基酸分布均衡,外源谷氨酸的添加显著影响氨基酸态氮水平。无添加的特级酱油(1号)、有增鲜剂添加的特级酱油(2号)和无增鲜剂添加的三级酱油(3号)的氨基酸总量分别为3.875、6.041和2.341 g/100 m L,其中2号样品含量最高;但在排除谷氨酸后1号样品氨基酸总量为3.494 g/100 m L,比2号和3号样品高14.11%和65.91%。1号样品必需氨基酸总量最高为2.08 g/100 m L,比2号和3号样品高18.18%和85.71%;2号样品氨基酸态氮检测值最高为1.42g/100 m L,其中谷氨酸的贡献率高达40.14%;3号样品的氨基酸总量和氨基酸态氮值均最低。     

Non-protein amino acids of plants

Protein forms the major nitrogenous constituent of plants, but other essential nitrogen-containing materials present in all plants include the nucleic acids, chlorophyll and indolylacetic acid. Some plant species produce secondary nitrogenous compounds such as alkaloids, cyanogenetic glucosides and non-protein amino acids. This paper discusses the group of more than 200 non-protein amino acids now characterised as plant products. Emphasis is placed on the variety of chemical structures encountered, upon the occurrence and biosynthesis of representative examples, and upon the toxic nature of certain compounds in relation to their behaviour as metabolic analogues or antagonists.     

氨基硅油柔软剂的分析

对氨基硅油柔软剂，采用溶剂提取、柱层析、碘代等方法进行预处理，以红外光谱、凝胶色谱、裂解色谱、质谱、气质联用和化学降解法对各组分进行定性检测及结构鉴定，采用重量法对各组分进行定量分析。     

氨烃基聚硅氧烷的应用性能研究

以N-(β-氨乙基)-γ-氨丙基聚二甲基硅氧烷ASO-1为例，利用差热分析仪、凝胶渗透色谱、扫描电镜等仪器对氨烃基聚硅氧烷的高分子物理性能和应用性能进行了系统研究。结果表明，侧链引入N-(β-氨乙基)-γ-氨丙基后，氨烃基聚硅氧烷的玻璃化温度Tg、介电常数ζ比主链结构相同的聚二甲基硅氧烷有所提高，粘温变化率、热耗损等相应增大；应用试验则表明，氨烃基聚硅氧烷的平均分子量增加，氨值增大，其柔软效果增强，其弱酸性使用条件以及适度较高的固化温度，有助于改善氨烃基聚硅氧烷的柔软效果。氨烃基聚硅氧烷不仅对纤维束有良好的松散作用，还可提高织物的断裂和撕破强度以及染色牢度，并产生抗静电效果。     

Method validation of 16 types of structural amino acids using an automated amino acid analyzer

An analytical method for the simultaneous determination of 16 types of structural amino acids in infant formula using an automated amino acid analyzer was validated through tests of precision, accuracy and linearity. The automated analysis of the amino acids was performed on an ion-exchange packed column with a visible detector. The certificated reference material (CRM) 1546 from NIST was used as the test sample to determine the precision and accuracy of the analytical method. The regression analyses revealed good correlations [correlation coefficient (r ²)] that were greater than 0.99. The recovery values of the amino acids were ranged from 87.18 to 118.08%. The limits of detection and limits of quantification were less than 0.059 mg/100 g and less than 0.198 mg/100 g, respectively. The intra- and inter-day precisions were less than 14.62% in the CRM sample.     

氨基酸营养价值评价方法的研究

通过查阅文献,随机选取31种常见食物氨基酸组成数据,利用统计学软件分析以粗蛋白为基数与以全氨基酸为基数下化学评析法中各项指标与生物价的相关性和离差情况。利用一元回归,求出化学评分法中各项指标与生物价的回归方程,求出值命名为化学生物价。结果表明:CS和SRCAA不随基数选择而改变,其他指标与BV的偏离高低不一。全氨基酸法计算的AAS、EAAI及EAARR与BV的相关性比粗蛋白法强。利用回归方程求得的化学生物价从总体上都消除了与BV的偏离。     

用氨基酸自动分析仪测定婴幼儿配方奶粉中的16种氨基酸

通过盐酸水解——氨基酸自动分析仪法,测定了婴幼儿配方奶粉中的16种氨基酸。结果表明,在12.5～250μmol/L的线性范围内相关系数均达到0.999以上,6组平行样的重复性变异系数均在2.0%以内,16种氨基酸3个浓度梯度的平均回收率均在95.0%～105.1%之间;应用盐酸水解法得到的待测液常温(20～28℃)放置5h及20h后,除Met外其余15种氨基酸5h后的平均损失率均在1%以下,Met的实际平均损失量也分别在5h0.005nmol/20μL和20h0.020nmol/20μL以下。结论说明,利用该法能得到十分理想的分离效果和相对准确的分析结果。     

天然食用香料浸膏中氨基酸的分析

采用酸水解法和氨基酸自动分析仪测定了茉莉浸膏、杭白菊浸膏、桂花浸膏、酒花浸膏、鸢尾浸膏、树兰花浸膏、枫槭浸膏和树苔浸膏共8类天然食用香料浸膏(共22个样品)中16种氨基酸的含量,如天冬氨酸(Asp)、苏氨酸(Thr)、丝氨酸(Ser)等。研究结果表明,除了茉莉浸膏、酒花浸膏、爱普鸢尾浸膏中未检测到氨基酸外,其他浸膏都含有氨基酸,种类基本相同,但氨基酸的总量均偏低,在5.29~833.54mg/100g之间;杭白菊浸膏中氨基酸的平均总量最高769.13mg/100g,其中拓普杭白菊浸膏氨基酸总量最高,为833.54mg/100g;树兰花浸膏中氨基酸平均总量最少6.135mg/100g,其中烟草树兰花浸膏中氨基酸总量最少,为5.29mg/100g。单因素方差分析结果表明,不同浸膏中氨基酸的含量具有显著性差异;聚类分析结果表明,所测浸膏主要分为两大类,第一大类包括树兰花浸膏、桂花浸膏、枫槭浸膏、树苔浸膏,第二大类是杭白菊浸膏。     

全自动氨基酸分析仪测定酱油中游离氨基酸的不确定度评定

该实验评定了全自动氨基酸分析仪测定酱油中游离氨基酸的不确定度。参考 CNAS-GL 006—2019《化学分析中不确定度的评估指南》和JJF 1059.1—2012《测量不确定度评定与表示》中的规定与要求,分析游离氨基酸在测定过程中的各种不确定度来源。在包含因子k=2时,酱油中游离氨基酸的扩展不确定度范围为0.02～0.60 g/100 g。结果表明,影响不确定度的主要因素是仪器本身的不确定度和酱油重复性测量的不确定度。     

反应型氨基硅油的制备

通过研究氨基硅油的合成、氨基硅油聚醚接枝工艺、氨基硅油异氰酸酯接枝工艺、残余异氰酸酯封端工艺等对合成速率及最终产品性能的影响,确定了合成聚醚异氰酸酯接枝氨基硅油即反应型氨基硅油的最佳合成工艺：聚醚改性剂用量24%（对氨基硅油质量）,反应温度75-85℃,反应时间3-4 h;异氰酸酯接枝70%（对氨基硅油中氨基含量）,反应温度55-70℃,反应时间2-4 h;残余异氰酸酯封端率65%,反应温度0-5℃,反应时间2-3h。     

对氨基酸测定的研究(上)

研究各种氨基酸的测定，介绍了氨基酸的测定方法，讨论了氨基酸检测的主要特点。     

氨基硅油柔软剂复配与应用的探索

研究了乳化剂品种选择与复配、氨基硅油与乳化剂的质量比、乳液pH、乳化温度、搅拌转速,复配氨基硅油柔软剂。该氨基硅油柔软剂与德国瓦克T730在棉或麻上进行应用试验对比,结果表明:氨基硅油柔软剂最佳复配条件为乳化剂质量比1350:1370:1390=1:2:1;氨基硅油与乳化剂质量比2:1;用醋酸中和氨基硅油pH至5～6;氨基硅油乳化温度15～25℃;搅拌转速1 000 r/min。氨基硅油质量比0.3N:0.6N:TP585=4:1:3,该氨基硅油柔软剂整理的棉或麻具有不黄变、不粘辊、手感柔软、平滑性能好等优点。     

Postharvest changes in ammonium,amino acids and enzymes of amino acid metabolism in asparagus spear tips

Harvested asparagus (Asparagus officinalis L) spears accumulate ammonium and amino acids in their tips during storage at ambient temperatures. To further investigate these phenomena the authors held spears at 20°C in the dark after harvest and examined several parameters of amino acid metabolism in the tips. Soluble protein content declined faster than total protein over the 5-day storage period. Protein loss was accompanied by an increase in total free amino acids with asparagine showing the most dramatic increase. A pronounced accumulation of ammonium occurred, starting after 3 days. The activities of glutamine synthetase (EC 6.3.1.2) and aspartate and alanine aminotransferases (EC 2.6.1.1 and EC 2.6.1.2, respectively) declined slightly whereas glutamate dehydrogenase (EC 1.4.1.2) activity almost doubled over 5 days. Phenylalanine ammonia lyase (EC 4.3.1.5) activity declined rapidly during the first 2 days and then partially recovered. Asparagine synthetase (EC 6.3.1.1), asparagine aminotransferase (EC 2.6.1.14), asparaginase (EC 3.5.1.1) and glutaminase (EC 3.5.1.2) activities were not detectable at any time during the storage period. Ammonium accumulation could be caused by increased glutamate dehydrogenase activity coupled with a shortage of aspartate.     

6种葡萄籽中水解氨基酸和游离氨基酸含量测定及比较

以异硫氰酸苯酯为柱前衍生试剂,采用Thermo Acclaim~(TM) 120 C_(18)色谱柱(250mm×4.6mm,5μm),流动相A为pH 6.5的乙酸钠缓冲溶液,流动相B为甲醇—乙腈—水(体积比20:60:20),在流速1.0mL/min,梯度洗脱,柱温30℃,检测波长254nm的条件下,建立了高效液相色谱法测定葡萄籽中水解氨基酸和游离氨基酸的含量。结果表明,在试验浓度范围内,17种氨基酸的R~2均0.999 0;水解氨基酸的加样回收率为92.0%～104.6%,RSD为0.83%～4.07%;游离氨基酸的加样回收率为95.2%～102.4%,RSD为1.06%～3.98%。同时,6种葡萄籽中水解氨基酸的含量为130.46～163.24 mg/g,游离氨基酸的含量为2.04～5.13mg/g;用于酿造白葡萄酒的雷司令、赛美容和贵人香3种葡萄籽中游离氨基酸含量较高,用于酿造红葡萄酒的黑皮诺、蛇龙珠和赤霞珠3种葡萄籽中水解氨基酸含量较高。该方法稳定可靠,可用于葡萄籽中水解氨基酸和游离氨基酸的含量测定。