酸水解蚕蛹制备复合氨基酸的研究

采用硫酸水解法,以蚕蛹制取复合氨基酸产品,得到氨基酸态氮分别为９．０５％和１３．４５％的食用复合氨基粉和精制复合氨基酸粉。食用复合氨基酸粉含有１８种氨基酸,其中必需氨基酸含量为３９．２％。食用复合氨基酸粉的制备方法经工厂小批量生产证实,其工艺简单易行,适合于中小企业采用,该产品的质量优良,生产成本低廉,具有市场竞争力。     

二次中和法制取菜籽复合氨基酸新工艺研究

为得到高质量的菜籽复合氨基酸,以脱皮菜籽粕为原料,研究了硫酸水解制备复合氨基酸的新工艺一二次中和法,解决了氨基酸脱色和副产品植酸的利用问题。水解的最佳工艺参数是3mol·L-1的H2SO4水解18h;ca(OH)2作中和剂,第一次中和和脱色的最佳pH为2-4,第二次中和的最佳pH为6.5-7.0,中和后的溶液经减压浓缩,喷雾干燥,制得菜籽复合氨基酸。复合氨基酸得率≥40％,纯度≥40％;副产品植酸钙得率10％左右,纯度40％-50％。     

酶法水解鲜猪血制备氨基酸的研究

本文以鲜猪血为主要原料,酶法水解制备氨基酸。其复合氨基酸收得率为１３．０７％·Ｗ／Ｖ）,分析测定表明除色氨酸含量含微量外,八种必需氨基酸的含量占复合氨基酸总量的４６．５２％。     

黄粉虫复合氨基酸的提取及氨基酸虫酒的制作

本研究在对黄粉虫幼虫所含的复合氨基酸3种提取方法及其所制成的氨基酸虫酒进行分析比较的基础上,得出最佳方案和数据：用酶解法处理虫浆可得到占干虫重31.5％酶解滤粉和31.06％复合氨基酸粉,是用水解法提取出复合氨基酸粉的2.1倍。在虫体原料重量相同的条件下,酶解滤粉酒中复合氨基酸浓度分别是水解滤粉酒和虫粉酒中复合氨基酸浓度的2.7和13倍。若制成氨基酸浓度为5mp／mL的虫酒,仅需幼虫21.5g,折合成用虫成本费0.5元左右。     

不依赖连接反应的高通量克隆方法

以脱脂菜籽粕酶解的复合氨基酸为主要原料,螯合率为考察指标,采用L16(4 5)正交试验设计,考察了pH值、温度、时间和配位比对螯合率的影响.结果显示,影响因素的高低顺序为:配位比＞pH值＞时间＞温度.结果表明,复合氨基酸与铜螯合的主要影响因素为pH值和配位比,且配位比的影响达到极显著水平.最佳工艺条件为:时间50 min,温度50℃,配位比2∶1,pH为9,此条件下的复合氨基酸螯合铜的螯合率为94.59％,氨基酸含量为30.2％.     

复合氨基酸注射液中氨基酸对山梨醇测定的影响与解决方法

复合氨基酸注射液如１１Ｓ、１４Ｓ中的氨基酸可使山梨醇的测定结果偏高６％,解决方法是将注射液通过磺酸型阳离子交换树脂柱,氨基酸成分在柱上被交换,山梨醇用水洗脱后测定。本方法对制订复合氨基酸类注射液的质量标准与确保产品质量均具有实际应用价值。     

鸡羽毛制备复合氨基酸铁铵的研究

本文介绍了以鸡羽毛为原料,采用盐酸水解,经与铁络合、调ＰＨ值制备复合氨基酸铁铵的方法。收率为４４．２％,总铁含量９．６％,游离铁含量０．４２％。废物充分利用,工艺简单易行。     

鸡羽毛制备复合氨基酸铁锭的研究

本文介绍了以鸡羽灵原料,采用盐酸水解,经与铁络合、调ＰＨ值制备复合氨基酸铁铵的方法。收率为４４．２％,部铁含量９．６％,游离铁含量０．４２％。施放的充分利用,工艺简单易行。     

盒子草氨基酸和糖类成分分析

本文通过对盒子草氨基酸和糖类成分分析,结果表明：总氨基酸含量为１１．３３％,其中人体必需氨基酸为４．９１％,碱性氨基酸为１．８３％,中性氨基酸为６．８２％,酸性氨基酸为２．６８％。总糖含量为１３．１３％,其中多糖为５．２９％,低聚糖为４．６８％,还原糖为３．１６％。     

鸭毛梗制备复合氨基酸工艺条件的研究

采用正交试验方法 ,研究了鸭毛梗水解制备复合氨基酸的工艺条件 ,结果表明 :温度 /压力是影响氨基酸转化率最主要的因素。鸭毛梗水解制备的复合氨基酸转化率盐酸法最高 (82 .36 % ) ,氢氧化钠法最低 (5 8.4 6 % ) ,硫酸法与盐酸法接近(79.4 4 % )。硫酸法产率较高 ,操作方便 ,环境污染和设备腐蚀均小 ,适合大量生产 ,确定为水解制备复合氨基酸介质 ,其最佳工艺条件为 :水解时间 8.0h ,硫酸浓度 3.0mol·L-1,水解温度 12 5℃。氨基酸分析表明 ,水解液中均含有 18种以上氨基酸。     

基于不同标度伪氨基酸组成预测脂肪酶的类型

从序列出发预测某蛋白质是否为脂肪酶以及属于哪种脂肪酶具有重要的理论和应用价值.提出了基于Z标度和T标度的伪氨基酸组成方法提取序列特征值,采用了k-近邻算法回答上述问题.经参数选择后,三种方法在各自最优运行参数下,其1倍交叉验证的结果为:对脂肪酶和非脂肪酶预测精度分别为92.8%、91.4%和91.3%;对脂肪酶类型预测的精度分别为92.3%、90.3%和89.7%.其中基于Z标度伪氨基酸组成效果最佳.基于T标度的次之,但均明显优于其他6种常见的特征值提取方法,并对其可能的原因进行了探讨.     

Within-host evolution of CD8+-TL epitopes encoded by overlapping and non-overlapping reading frames of simian immunodeficiency virus

In order to understand the impact of overlapping reading frames on natural selection by host CD8+ T lymphocytes (CD8(+)-TL), we analyzed the pattern of nucleotide substitution in simian immunodeficiency virus (SIV) genomes sampled from populations at time of death in 35 rhesus monkeys. Both the mean number of nonsynonymous nucleotide substitutions per nonsynonymous site (d(N)) and the mean number of synonymous nucleotide substitutions per synonymous site (d(S)) were elevated in overlap regions in comparison to non-overlap regions. Mean d(N) exceeded mean d(S) in CD8(+)-TL epitopes restricted by the host's class I major histocompatibility complex molecules. This pattern, which is indicative of positive Darwinian selection favoring amino acid changes in these epitopes, was seen in both overlap and non-overlap regions; but mean d(N) was particularly elevated in restricted CD8(+)-TL epitopes encoded in overlap regions. Amino acid changes from the inoculum were defined as parallel if the same amino acid change occurred at the same site independently in two or more monkeys, and a surprisingly high proportion (71.9%) of observed amino acid changes throughout the SIV genome occurred in parallel in different monkeys. The proportion of parallel changes in restricted epitopes encoded by overlapping reading frames was still higher (80%), supporting the hypothesis that the interaction of positive selection and overlapping reading frames enhances the probability of convergent or parallel amino acid change.     

III. The RNA component of aminoacyl-tRNA synthetase complexes isolated from mouse liver. Absence of amino acid accepting activity.

A method is described which permits the simultaneous isolation and separation of insoluble aminoacyl-tRNA synthetase protein - RNA complexes containing high specific synthetase activity, and soluble tRNA which retains 25% to 50% of its specific amino acid accepting activity. A possible amino acid accepting activity of the RNA part of the insoluble aminoacyl-tRNA synthetase protein - RNA complex was investigated by assaying the unchanged complex and the RNA obtained after dissociation from the protein part of the synthetase complex. No amino acid accepting activity was found.     

Effect of microbial phytase on apparent ileal amino acid digestibility of phosphorus-adequate diets in growing pigs

Six ileally cannulated pigs (mean initial body weight 34.8 kg) were used to study the effect of microbial phytase on apparent ileal digestibility of P, total N and amino acids. Three P-adequate diets (digestible P concentration 2.3 g kg(- )l) containing barley (B), soyabean meal (S) or a mixture of the two (BS) with or without phytase supplement (1000 FTU x kg(-1)) were fed to pigs using a 6 x 6 Latin square design. The addition of phytase increased (p < 0.05) apparent ileal P digestibility of diets B, S and BS by 16.5, 19.2 and 19.2%, respectively. There was no effect of phytase on the ileal digestibility of total N. Apparent ileal digestibility of amino acids tended to increase in the BS diet supplemented with phytase (mean improvement of 2.2%); but no significant difference was found for any amino acid as compared with the unsupplemented diet. To asses the additivity of apparent amino acid digestibility, the determined values for the BS diet were compared to those calculated from digestibilities found in diets B and S. There were no significant differences between the determined and calculated values. It is concluded that the addition of microbial phytase to P-adequate diets does not affect ileal amino acid digestibility in growing pigs and that the apparent amino acid digestibility values determined in single ingredients may be additive when included into a complex diet.     

用猪血制备复合氨基酸及其应用的研究

<正> 我国猪血资源非常丰富,据统计,江苏省各肉联厂的猪血全部收集起来,每年可制成血粉约8000吨,全国大约是这个数字的10倍。但是这些猪血的大部分没有利用,既浪费了资源又污染了环境。猪血中含有大量的蛋白质,如何充分而合理地利用猪血中的蛋     

Why is the biological hydrophobicity scale more accurate than earlier experimental hydrophobicity scales?

The recognition of transmembrane helices by the translocon is primarily guided by the average hydrophobicity of the potential transmembrane helix. However, the exact hydrophobicity of each amino acid can be identified in several different ways. The free energy of transfer for amino acid analogues between a hydrophobic media, for example, octanol and water can be measured or obtained from simulations, the hydrophobicity can also be estimated by statistical properties from known transmembrane segments and finally the contribution of each amino acid type for the probability of translocon recognition has recently been measured directly. Although these scales correlate quite well, there are clear differences between them and it is not well understood which scale represents neither the biology best nor what the differences are. Here, we try to provide some answers to this by studying the ability of different scales to recognize transmembrane helices and predict the topology of transmembrane proteins. From this analysis it is clear that the biological hydrophobicity scale as well scales created from statistical analysis of membrane helices perform better than earlier experimental scales that are mainly based on measurements of amino acid analogs and not directly on transmembrane helix recognition. Using these results we identified the properties of the scales that perform better than other scales. We find, for instance, that the better performing scales consider proline more hydrophilic. This shows that transmembrane recognition is not only governed by pure hydrophobicity but also by the helix preferences for amino acids, as proline is a strong helix breaker. Proteins 2014; 82:2190–2198. © 2014 Wiley Periodicals, Inc.     

Physical properties of type I collagen extracted from fish scales of Pagrus major and Oreochromis niloticas

Type I collagens were extracted from fish scales of Pagrus major and Oreochromis niloticas as a possible underutilized resource for medical materials. The fish scales were demineralized with EDTA and digested by pepsin. The resultant type I collagens contained more than 33.6% of glycine as the most abundant amino acid. The denaturation temperatures of the collagens from P. major and O. niloticas were 303 and 308 K, respectively, both of which were relatively lower than that of porcine dermis collagen (314 K). CD spectra indicated that the denaturation temperatures were dependent on the amount of hydroxyproline, rather than proline residues. Raman spectra also indicated that the relative intensities of Raman lines at 879 and 855 cm⁻¹ assigned to Hyp and Pro rings were changed due to the contents of the imino acids. Significantly, the content of sulphur-containing methionine was higher in the fish scales than in porcine dermis. The enthalpy and entropy estimated from thermal analyses could be correlated to amino acid sequences (Gly-Pro-Hyp) of type I collagens and the number of methionine amino acid residues.     

Ultrasonic velocity assay of extracellular invertase in living yeasts

Being the largest family of cell surface receptors, G-protein-coupled receptors (GPCRs) are among the most frequent targets. The functions of many GPCRs are unknown, and it is both time-consuming and expensive to determine their ligands and signaling pathways by experimental methods. It is of great practical significance to develop an automated and reliable method for classification of GPCRs. In this study, a novel method based on the concept of Chou’s pseudo amino acid composition has been developed for predicting and recognizing GPCRs. The discrete wavelet transform was used to extract feature vectors from the hydrophobicity scales of amino acid to construct pseudo amino acid (PseAA) composition for training support vector machine. The prediction accuracies by the current method among the major families of GPCRs, subfamilies of class A, and types of amine receptors were 99.72%, 97.64%, and 99.20%, respectively, showing 9.4% to 18.0% improvement over other existing methods and indicating that the proposed method is a useful automated tool in identifying GPCRs.     

低温贮藏期间百合鳞茎中的游离氨基酸组分和含量变化

百合鳞茎的游离氨基酸主要集中在顶芽和内部鳞片等幼嫩组织中,含量最高、变化最大的是精氨酸.谷氨酸族的氨基酸在鳞茎代谢中起重要作用.顶芽的氨基酸总量及精氨酸含量随贮藏温度的升高而增加.贮藏过程中,鳞茎盘的氨基酸含量下降,顶芽和贮备组织中其含量有明显升高的过程.贮藏前期34 d内游离氨基酸含量发生显著变化.