苦豆子游离氨基酸的成份测定

本文分析和鉴定了苦豆子中游离氨基酸的成份,测定出１６种游离氨基酸,总量为１６４．５２μｇ／１００ｍｇ,其中谷氨酸含量最高为４７．６８μｇ／１００ｍｇ,蛋氨酸含量最低为０．２０μｇ／１００ｍｇ,人体必须氨基酸有７种,占游离氨基酸总量的１７．３３％。     

野苋菜的氨基酸含量与营养评价

野苋菜含有１８种氨基酸,其中有营养必需的８种氨基酸。含硫氨基酸ＡＡＳ＝０．５１,为第一限制氨基酸。Ｅ／Ｅ＋Ｎ＝４１．６％,Ｅ／Ｎ＝０．７１,接近ＷＨＯ／ＦＡＯ提出的参考蛋白模式。     

银杏叶中氨基酸的含量测定

本文测定了不同时期采集的银杏树叶中１７种氨基酸的含量。结果表明,银杏叶中水解氨基酸的总含量分别为１５．０９％,１１．８７％,９．９７％,和７．１４％;游离氨基酸的总含量分别为０．７６％,０．２８％。     

脑出血和脑梗死患者血清谷氨酸,甘氨酸和丙氨酸浓度的改变及意义

目的探讨血清中谷氨酸、甘氨酸和丙氨酸含量变化与脑出血和脑梗死的关系,为今后临床深入研究提供参考资料。方法用氨基酸分析仪对２３例急性脑出血和２６例脑梗死病人谷氨酸、甘氨酸和丙氨酸进行测定,并与对照组进行比较。结果病人组的兴奋性氨基酸谷氨酸的含量明显高于对照组（Ｐ＜０．０１）,病人组的抑制性氨基酸甘氨酸和丙氨酸的含量与对照组无显著差异（Ｐ＞０．０５）。结论提示兴奋性氨基酸谷氨酸可能作为损伤因素参与脑出血和脑梗死脑损伤的发生。     

鸡肠中氨基酸含量的高效液相色谱分析

本文采用以异硫氰酸苯酯（ＰＩＴＣ）为柱前衍生化的高效液相色谱法测定氨基酸,并对方法测定条件进行了研究,得出流动相ｐＨ６．４０时测定的ＲＳＤ值最低,为０．５９％,样品经微波水解７ｍｉｎ（３００Ｗ功率）,且稀释液加入５ｍｉｎ后进样方能得到最佳结果。用本法对鸡肠中氨基酸进行了分析,必需氨基酸总量占３４．９％,具有可开发利用之价值。     

从绢纺厂废丝提取氨基酸──水解时间与氨基酸含量的关系

本研究利用绢纺厂废丝为原料,在６ｍｏｌ／Ｌ盐酸１１０℃条件下进行水解,探讨水解时间与氨基酸含量之间的关系。试验结果经数理统计表明：它们之间的关系符合方程ｙ＝ａ＋ｂｘ＋ｃｘ￣２,大部分单一氨基酸和混合氨基酸在被水解１５小时左右时,其含量最高。实验也表明绢纺废丝的氨基酸含量在９５％以上。     

底物膜技术检测精子顶体酶活性的研究

应用底物膜技术检测１３０例正常精液,精子顶体酶活性百分率的正常值下限为５７％。４５９例不孕症病人精液分析,无精症２５例,其余４３４例中７５％精子顶体酶活性正常。实验表明精子密度对数值与顶体酶活性百分率之间有正相关,ｒ＝０．８４（Ｐ＜０．０１）,回归方程为顶体酶活性百分率ｙ＝４８．４３％＋（８．９％）（ｌｏｇ精子计数）。活动精子百分率与顶体酶活性之间有密切正相关,ｒ＝０．９６７,（Ｐ＜０．０１）,顶体酶活性ｙ＝３８．６％＋０、３６ｘ％。前向活跃直线运动精子百分率与顶体酶活性之间也有密切相关．ｒ＝０．９６,（Ｐ＜０．０１）,顶体酶活性ｙ＝３４．２１％＋０．６１ｘ％。     

氨基酸分析的准确度和精确度

五个实验室分两部分协作研究改进和测定氨基酸分析的准确皮和精确度。末公开发表的第一部分结果由各实验室按照自己的最佳实验操作处理。本文报道第二部分,分析了三个纯化的和六个常规的蛋白质,每种蛋白质用三种不同的方法处理（常规水解、延长水解和下文提及到的氧化水解）。文献中报道的结果得到了证实,尽管其结果不太一致,还常有一些特殊的结果。得到文献充分证明的处理结果对于分析工作适应不同的要求是必不可少的。由于重复性变异较高,没有对某一个实验结果做进一步的统计分析。重复性（实验室内部）的变异系数为４．１％,再现性（实验室之间）的变异系数为１３．１％。纯化蛋白的最佳氨基酸估计和根据一个实验室的５个氨基酸与另一个实验室的５个氨基酸的偏差提供的排列顺序（Ｐ＜０．０１）计算的估计是不符的。对常规蛋白质结果的删除临界值采用Ｐ＜０．０１时,最佳估计的９．９％被删除,偏差为８．１％,奇异值为３．２％,偏差和奇异共有者为１．３％。当这些值被删除时,１９／９６平均值变化不超过４％,９／９６变化为４～８％,８／９６变化更大些,集合的变异系数由８．２％降到５．４％。在这种临界值下,常规蛋白质的每个实验室结果中有０～３１％删除。在较低的临界值（Ｐ＜?     

抗植物病毒农药“病毒煞”的氨基酸成分分析

本文通过对抗植物病毒农药“病毒煞”的氨基酸成分进行分析,共含有１８种氨基酸,其中脯氨酸、谷氨酸、精氨酸和天冬氨酸含量较高,约占水解氨基酸总量的４７％;含有１９种游离氨基酸,脯氨酸含量最高,占游离氨基酸总量的５１％,说明氨基酸可能是其防病增产的有效成分之一。     

PICO-TAG方法测定氨基酸的研究

详细讨论了用异硫氰酸苯酯（ＰＩＴＣ）柱前衍生,反相色谱法测定氨基酸（即ＰＩＣＯ－ＴＡＧ法）的最佳条件。研究了流动相配制时溶液ｐＨ值、乙腈含量等对色谱分析的影响,并且对色谱柱的退化与再生进行了说明。氨基酸含量在１．２５～１５００ｐｍｏｌ范围内线性良好,相关系数大于０．９９９,且大多数氨基酸保留时间的变异系数小于０．５％。氨基酸采用峰面积定量,测定变异系数为０．１～１．５％。     

吊瓜籽中氨基酸质量分数的测定

样品吊瓜籽经酸水解处理,应用氨基酸分析仪进行分析,结果表明,吊瓜籽含所有常规17种氨基酸,质量分数高达23.28%,其中谷氨酸(G lu)和精氨酸(Agr)质量分数达4.39%和3.88%。     

Folic Acid Production by Engineered Ashbya gossypii

Folic acid (vitamin B₉) is the common name of a number of chemically related compounds (folates), which play a central role as cofactors in one-carbon transfer reactions. Folates are involved in the biosynthesis and metabolism of nucleotides and amino acids, as well as supplying methyl groups to a broad range of substrates, such as hormones, DNA, proteins, and lipids, as part of the methyl cycle. Humans and animals cannot synthesize folic acid and, therefore, need them in the diet. Folic acid deficiency is an important and underestimated problem of micronutrient malnutrition affecting billions of people worldwide. Therefore, the addition of folic acid as food additive has become mandatory in many countries thus contributing to a growing demand of the vitamin. At present, folic acid is exclusively produced by chemical synthesis despite its associated environmental burdens. In this work, we have metabolically engineered the industrial fungus Ashbya gossypii in order to explore its potential as a natural producer of folic acid. Overexpression of FOL genes greatly enhanced the synthesis of folates and identified GTP cyclohydrolase I as the limiting step. Metabolic flux redirection from competing pathways also stimulated folic acid production. Finally, combinatorial engineering synergistically increased the production of different bioactive forms of the folic vitamin. Overall, strains were constructed which produce 146-fold (6595 µg/L) more vitamin than the wild-type and by far represents the highest yield reported.     

果树种子氨基酸含量比较

果树种子中17种氨基酸总量以仁果类最高,其次是核果类、浆果类和坚果类。种子中人体必需的八种氨基酸占总量的比率,浆果高于坚果、核果、仁果。种子含谷氨酸最多,天门冬氨酸、精氨酸、蛋氨酸等次之,组氨酸、丙氨酸、胱氨酸最少。     

人工栽培花脸香蘑氨基酸研究

从野生花脸香蘑中分离 ,纯化获得花脸香蘑菌株 ,用稻草代料栽培获得花脸香蘑子实体。用Backman 6 30 0自动氨基酸分析仪首次测定了人工代料栽培的花脸香蘑子实体中 18种氨基酸。结果显示 ,花脸香蘑子实体干品中 ,蛋白质质量分数为30 .0 3% ;18种氨基酸质量分数为 2 4 .37% ,其中谷氨酸 4 .79% ,天门冬氨酸 2 .4 6 % ,赖氨酸 1.6 0 % ,色氨酸 0 .4 8% ,蛋氨酸 0 .4 3%。该分析结果对花脸香蘑的研究开发具有科学价值     

荞麦中氨基酸含量的分析

采用日立８３５—５０型氨基酸分析仪,测定了九个品种荞麦的氨基酸含量,结果表明：①谷氨酸的含量在荞麦中的比例最高。②荞麦中赖氨酸的含量高于一般谷实类赖氨酸的含量。③苦荞与甜荞之间在氨基酸总量上无显著性差异。     

Folic Acid Supplementation Promotes Mammary Tumor Progression in a Rat Model

Folic acid supplementation may prevent the development of cancer in normal tissues but may promote the progression of established (pre)neoplastic lesions. However, whether or not folic acid supplementation can promote the progression of established (pre)neoplastic mammary lesions is unknown. This is a critically important issue because breast cancer patients and survivors in North America are likely exposed to high levels of folic acid owing to folic acid fortification and widespread supplemental use after cancer diagnosis. We investigated whether folic acid supplementation can promote the progression of established mammary tumors. Female Sprague-Dawley rats were placed on a control diet and mammary tumors were initiated with 7,12-dimethylbenza[a]anthracene at puberty. When the sentinel tumor reached a predefined size, rats were randomized to receive a diet containing the control, 2.5x, 4x, or 5x supplemental levels of folic acid for up to 12 weeks. The sentinel mammary tumor growth was monitored weekly. At necropsy, the sentinel and all other mammary tumors were analyzed histologically. The effect of folic acid supplementation on the expression of proteins involved in proliferation, apoptosis, and mammary tumorigenesis was determined in representative sentinel adenocarcinomas. Although no clear dose-response relationship was observed, folic acid supplementation significantly promoted the progression of the sentinel mammary tumors and was associated with significantly higher sentinel mammary tumor weight and volume compared with the control diet. Furthermore, folic acid supplementation was associated with significantly higher weight and volume of all mammary tumors. The most significant and consistent mammary tumor-promoting effect was observed with the 2.5x supplemental level of folic acid. Folic acid supplementation was also associated with an increased expression of BAX, PARP, and HER2. Our data suggest that folic acid supplementation may promote the progression of established mammary tumors. The potential tumor-promoting effect of folic acid supplementation in breast cancer patients and survivors needs further clarification.     

Two distinct types of cell surface folic acid-binding proteins in Dictyostelium discoideum

Folic acid is degraded too fast by Dictyostelium discoideum to study binding of this ligand to cell surface binding proteins. Folate deaminase activity was inhibited in the presence of 3.3 × 10⁻⁴ M 8-azaguanine. This inhibitor enabled us to detect two folate binding proteins. One type bound folic acid and deamino-folic acid with the same affinity (K_0.5 = 3–6 × 10⁻⁷ M) and apparently negative cooperativity. Binding to only this type was observed if 8-azaguanine was omitted. The second type bound folic acid noncooperatively with K_d = 7 × 10⁻⁷ M. Deamino-folic acid did not compete even at a 1000-fold excess. This type may correspond to the chemotactic receptor.     

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。     

叶酸对心脑血管疾病二级预防作用的研究

目的:探讨叶酸对心脑血管疾病二级预防的效果。方法:326例恢复期心脑血管疾病患者以自愿的原则分为实验组(n=201)和对照组(n=125),对照组针对病因应用常规药物,实验组在针对病因常规用药的基础上应用叶酸,随访三年,所有患者均在实验前和半年后测一次血清同型半胱氨酸含量,同时记录对比两组心脑血管不良事件的发生率。结果:323例纳入统计,实验组和对照组在入选时同型半胱氨酸含量无差异(P>0.05),半年后实验组血清同型半胱氨酸含量显著低于对照组(P<0.05);心绞痛、心力衰竭、血栓形成等发生率差异均具有统计学意义(均为P<0.05),而在心肌梗死、脑梗死和病死率等方面差异没有统计学意义(P>0.05)。结论:叶酸在心脑血管疾病二级预防中可以降低心绞痛发生率、心力衰竭、血栓形成的发生率,对心肌梗死、脑梗死和病死率没有明显的影响。     

叶酸与蛋白质合成

叶酸作为一碳单位携带分子,在机体内发挥着非常重要的作用,它所参与的甲基化作用与蛋白质的合成紧密相关,本文对叶酸影响蛋白质的合成过程做了比较全面的综述,旨在阐明叶酸在蛋白质合成各个阶段中的作用。