纸层析法测定缬氨酸含量的改良

改进了缬氨酸含量的测定方法。探讨了茚三酮与缬氨酸完全反应的质量分数范围;将传统的静置洗脱更改为匀速摇床洗脱,使洗脱更完全;在此基础上,详细研究了操作过程中的相关参数,使结果更精确。结果表明,该方法有很高的准确度和精密度,操作简便,成本低,可以广泛应用于茚三酮反应测定氨基酸。     

Amino acids,fatty acids,and dietary fibre in edible seaweed products

The nutritional compositions of 34 edible seaweed products of the Laminaria sp., Undaria pinnatifida, Hizikia fusiforme and Porphyra sp. varieties were analyzed.     

三氯化缬氨酸六水合钆配合物的热分解机理与活化能研究

以氧化钆、缬氨酸、盐酸为原料,合成了三氯化缬氨酸六水合钆配合物,通过EDTA滴定、元素分析、红外光谱分析、熔点测定对该配合物的组成和性质进行了分析和表征,利用热重、差热分析等方法推测了配合物的热分解机理,利用动力学中Achar-Brindley-Sharp-Wendworth和Coats-Red-fern法对配合物热分解过程氨基酸骨架断裂第一步反应进行了非等温动力学研究,得出该步热分解反应的活化能(E)为302.88 kJ/mol,指前因子的对数值ln(A/s-1)为54.21,动力学方程式为ddTα=Aβexp-RET.23[(1-α)-1/3-1]-1。     

缬氨酸在畜禽和水产生产中的研究进展

缬氨酸是一种支链氨基酸,在生命体内物质代谢调控和信息传递等许多方面扮演着重要角色,广泛应用于营养添加剂、饲料添加剂、调味品、医药、农药和保健品等方面。本文综述了缬氨酸在畜禽和水产生产中的应用,缬氨酸能改善母猪母乳营养成分,促进仔猪生长,提高家禽生产性能,以及在水产生产方面的影响。同时,还对生产缬氨酸的主要技术路线及应用有关进展情况与前景作介绍。     

Production of optically pure L‐valine in fluidized and packed bed reactors with immobilized L‐aminoacylase

A process to obtain L ‐valine has been developed using fluidized and packed bed reactors with L ‐aminoacylase (from hog kidney) immobilized by covalent binding. L ‐Valine production using the immobilized derivative of L ‐aminoacylase in fluidized and packed bed reactors was studied at three different substrate concentrations and two different flow rates. Higher productions were obtained in the packed bed reactor in all cases. The different solubilities of L ‐valine and acetyl‐D ‐valine in ethanol were used to purify L ‐amino acid from the reactor effluents. The amount of added ethanol did not influence the separation yields, although the purity of L ‐valine was strongly affected by this parameter. The last step involved was racemization of the unhydrolyzed acetyl‐D ‐valine, which was then used as substrate in a new reaction cycle. © 1999 Society of Chemical Industry     

生物素和VB1在谷氨酸棒杆菌过量合成缬氨酸中的作用

通过对谷氨酸棒杆菌突变株AATV341进行生物素和VB1添加量的实验，探讨了生物素和VB1添加量对该菌株菌体质量及缬氨酸产量的影响；同时根据对AATV341进行的胞内外某些特定氨基酸和有机酸检测，研究了这两种维生素对碳架代谢流的分布，尤其是对丙酮酸节点处的代谢流量分布的影响。结果表明，生物素添加量在40μg／L时，菌体质量和缬氨酸在胞外的累积明显提高，谷氨酸在胞外累积降低；VB1的适量添加，可提高缬氨酸在胞外的累积，降低发酵液中乙酸和草酰乙酸的含量。     

模拟移动床技术分离缬氨酸和丙氨酸

研究了线性条件下模拟移动床分离缬氨酸和丙氨酸的行为,掌握了模拟移动床的基本运行规律,实现了2种中性氨基酸的分离,分离效果远好于普通的分离方法,得到了较高纯度的缬氨酸(98.6%)和丙氨酸(82.9%)产品,提高了生产效率。     

BCAA Metabolism and Insulin Sensitivity – Dysregulated by Metabolic Status?

Branched‐chain amino acids (BCAAs) appear to influence several synthetic and catabolic cellular signaling cascades leading to altered phenotypes in mammals. BCAAs are most notably known to increase protein synthesis through modulating protein translation, explaining their appeal to resistance and endurance athletes for muscle hypertrophy, expedited recovery, and preservation of lean body mass. In addition to anabolic effects, BCAAs may increase mitochondrial content in skeletal muscle and adipocytes, possibly enhancing oxidative capacity. However, elevated circulating BCAA levels have been correlated with severity of insulin resistance. It is hypothesized that elevated circulating BCAAs observed in insulin resistance may result from dysregulated BCAA degradation. This review summarizes original reports that investigated the ability of BCAAs to alter glucose uptake in consequential cell types and experimental models. The review also discusses the interplay of BCAAs with other metabolic factors, and the role of excess lipid (and possibly energy excess) in the dysregulation of BCAA catabolism. Lastly, this article provides a working hypothesis of the mechanism(s) by which lipids may contribute to altered BCAA catabolism, which often accompanies metabolic disease.     

N-(甲酰基吡嗪)-α-氨基酸甲酯的合成

以2,3-吡嗪二羧酸和α-氨基酸(甘氨酸、缬氨酸、亮氨酸)为原料,在氯化亚砜的作用下,采取分步法和一步法,得到不同的吡嗪酰胺类衍生物,其结构经1HNMR、13CNMR、IR和HR-MS等方法确定。探讨了不同反应条件对吡嗪酰胺类衍生物合成的影响。结果表明,在氯化亚砜的作用下,采用分步法和一步法,分别得到N-(2-羧基-3-甲酰基吡嗪)-α-氨基酸甲酯和N-(2,3-二甲酰基吡嗪)-α-氨基酸甲酯。其最优反应条件为:在分步法和一步法中,α-氨基酸甲酯盐酸盐与Et3N的摩尔比约为1∶2.1时,氨基释放完全,目标产物的收率最高;分步法2,3-吡嗪二甲酰氯盐酸盐的制备采用直接抽滤为最优方法,收率达75%以上;一步法N-(2,3-二甲酰基吡嗪)-α-氨基酸甲酯的制备中,氯化亚砜的量为6 mL时,收率最高。从整体来看,分步法的收率较高,均50%以上。