真菌菌丝体和发酵液的氨基酸分析比较

<正> 对云芝等7种真菌的菌丝体和发酵液分别测定17种氨基酸的含量,测定结果表明这些菌丝体中含有丰富的人体8种必需氨基酸,支链氨基酸及精氨酸,而芳香族氨基酸和含硫氨基酸却很低。7种真菌的菌丝体和它们的子实体,和三种食用蛋白(α-酪蛋白,卵白蛋白,大豆球蛋白)及4种粮食产品     

Amino Acid Pool Formation in Pseudomonas aeruginosa

The accumulation and behavior of various amino acids in the pool of Pseudomonas aeruginosa (ATCC 9027) were investigated. Patterns of pool formation and maintenance varied with different amino acids tested and were dependent, to a considerable extent, upon the ability of the organism to catabolize the particular amino acid. The establishment of steady-state amino acid pool levels depended upon the activity of the amino acid permease involved and upon the rate of protein synthesis. The presence of a relatively large specific amino acid pool did not affect the formation of a pool of a structurally different amino acid, and a preformed steady-state pool was not displaced by structurally unrelated amino acids. Steady-state amino acid pools decreased rapidly in the presence of inhibitors of energy metabolism and at 0 C. Steady-state internal amino acid pools were found to be in equilibrium with the corresponding external amino acid, present at low levels. A multiplicity of proline pools was demonstrated.     

Some features of the regulation of the free amino acids in adult Calliphora erythrocephala

The amounts of nearly every amino acid in Calliphora remain unchanged inspite of stress. Thus the free amino acid pool is regulated. The amounts of free amino acid in the haemolymph account for only a small part of the total free amino acid in a fly and therefore most free amino acid is located and regulated intracellularly. A comparison of the rates of conversion and turnover of glycine-C¹⁴ in flies fed protein and sugar and in flies fed sugar alone indicates that in the absence of a dietary source of amino acid, not only is the rate of total turnover appreciably lower but the rates of conversion to other amino acids also change. With a dietary source of amino acid, the rates of incorporation into protein account for only a part of the total turnover of each amino acid. With a sufficiency of amino acid, substantial amounts are probably used as an energy source.     

地黄炮制过程氨基酸组分分析

利用氨基酸自动分析仪分别测定加工前后地黄中的总氨基酸和游离氨基酸质量分数。分析、比较炮制前后地黄的氨基酸成分变化。炮制前后地黄的氨基酸种类及含量有明显变化,多数氨基酸的含量在炮制后明显下降甚至消失。结论:炮制前后的地黄中氨基酸质量分数差别明显,其中碱性氨基酸质量分数的差别尤其显著,该差异可能是由于炮制过程中发生美拉德反应造成的。     

平衡型氨基酸透析液对维持性血液透析患者血浆游离氨基酸含量的影响

目的:研究一种平衡型氨基酸透析液,探讨其对维持性血透患者血游离氨基酸含量的影响。方法:实验采用自身对照设计,应用蛋白水解法测定、分析应用氨基酸透析液血透前后患者血浆氨基酸含量,并同时测定应用碳酸盐透析液患者及健康人血浆游离氨基酸作为比较。结果:经碳酸盐透析后,患者血浆大多数游离氨基酸和总氨基酸含量显著降低。给予平衡氨基酸透析液能不同程度改善患者血浆游离氨基酸的含量。结论:平衡型氨基酸透析液能减少血中部分氨基酸的丢失。     

基因型和地域分布对小麦籽粒氨基酸含量影响的研究

根据河南省7个试验基点的10个小麦基因型籽粒中17种氨基酸含量的测定结果,对不同基因型氨基酸含量差异及其地域分布进行了研究,结果表明,小麦籽粒氨基酸含量不仅存在基因型的差异,而且在很大程度上受生态环境条件的影响,环境间氨基酸含量的变异明显大于基因型,约为基因型间变异的1．5倍。不同试点所对应的气候分布、土壤类型与氨基酸含量变异有较大的吻合程度,表现出随湿润条件增加,氨基酸含量和必需氨基酸、非必需氨基酸总量逐渐下降,而非必需氨基酸占氨基酸总量的比例呈逐渐上升趋势,与人体代谢关系密切的赖氨酸化学记分较 低,且变异较小。     

Molecular and functional characterization of a family of amino acid transporters from Arabidopsis

More than 50 distinct amino acid transporter genes have been identified in the genome of Arabidopsis, indicating that transport of amino acids across membranes is a highly complex feature in plants. Based on sequence similarity, these transporters can be divided into two major superfamilies: the amino acid transporter family and the amino acid polyamine choline transporter family. Currently, mainly transporters of the amino acid transporter family have been characterized. Here, a molecular and functional characterization of amino acid polyamine choline transporters is presented, namely the cationic amino acid transporter (CAT) subfamily. CAT5 functions as a high-affinity, basic amino acid transporter at the plasma membrane. Uptake of toxic amino acid analogs implies that neutral or acidic amino acids are preferentially transported by CAT3, CAT6, and CAT8. The expression profiles suggest that CAT5 may function in reuptake of leaking amino acids at the leaf margin, while CAT8 is expressed in young and rapidly dividing tissues such as young leaves and root apical meristem. CAT2 is localized to the tonoplast in transformed Arabidopsis protoplasts and thus may encode the long-sought vacuolar amino acid transporter.     

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。     

Identification and analysis of novel amino acid sequence repeats and domains in Pyrobaculum aerophilum using computational tools

We have identified four repeats and five domains that are novel in proteins encoded by the Pyrobaculum aerophilum str. IM2 proteome using automated in silico methods. A "repeat" corresponds to a region comprising less than 55 amino acid residues that occurs more than once in the protein sequence and sometimes present in tandem. A "domain" corresponds to a conserved region comprising greater than 55 amino acid residues and may be present as single or multiple copies in the protein sequence. These correspond to (1) 85 amino acid residues AAG domain, (2) 72 amino acid residues GFGN domain, (3) 43 amino acid residues KGG repeat, (4) 25 amino acid residues RWE repeat, (5) 25 amino acid residues RID repeat, (6) 108 amino acid residues NDFA domain, (7) 140 amino acid residues VxY domain, (8) 35 amino acid residues LLPN repeat and (9) 98 amino acid residues GxY domain. A repeat or domain is characterized by specific conserved sequence motifs. We discuss the presence of these repeats and domains in proteins from other genomes and their probable secondary structure.     

Determination of amino acid pairs sensitive to variants in human beta-glucocerebrosidase by means of a random approach

In this data-based theoretical analysis, we use the random approach to analyse the amino acid pairs in human beta-glucocerebrosidase in order to determine which amino acid pairs are more sensitive to 109 variants from missense mutant human glucocerebrosidase. The rationale of this study is based on our hypothesis and findings that the harmful variants are more likely to occur at randomly unpredictable amino acid pairs and the non-harmful variants are more likely to occur at randomly predictable amino acid pairs. This is because we argue that the randomly predictable amino acid pairs should not be deliberately evolved, whereas the randomly unpredictable amino acid pairs should be deliberately evolved with connection of protein function. The results show, for example, that 93.58% of 109 variants occur at randomly unpredictable amino acid pairs, which account for 71.40% of amino acid pairs in glucocerebrosidase, and the chance of occurrence of the variant is about 4.4 times higher in randomly unpredictable amino acid pairs than in predictable pairs. Hence the randomly unpredictable amino acid pairs are more sensitive to variants in human glucocerebrosidase. The results also suggest that human glucocerebrosidase has a natural tendency to variants.     

Influence of triiodothyronine and dexamethasone on renal amino acid handling in rats loaded with various amino acid mixtures

Summary In adult female rats, the influence of dexamethasone or triiodothyronine on renal amino acid handling was investigated in amino acid loaded animals. Amino acids were administered intravenously as two mixtures, each containing four amino acids to overload amino acid reabsorption capacity. Bolus injections of both mixtures were followed by temporary increase in fractional excretion of the administered amino acids as well of the amino acids which were not covered in the mixtures. The administration of the two mixtures was followed by different interactions between various amino acid carriers.After dexamethasone pretreatment (60µg/100g b.wt. for 3 days, once daily) a stimulation of the renal amino acid handling could be shown. Triiodothyronine (20µg/100g b.wt. for 3 days, once daily) did not increase tubular reabsorption capacity for amino acids. It even increased fractional amino acid excretion in amino acid loaded rats as a sign of enhanced amino acid metabolism in the kidney and/or increased amino acid uptake into the tubular cells from the luminal site.     

Estimation of amino acid pairs sensitive to variants in human phenylalanine hydroxylase protein by means of a random approach

In this data-based theoretical analysis, we use a random approach to estimate amino acid pairs in human phenylalanine 4-hydroxylase (PAH) protein in order to determine which amino acid pairs are more sensitive to 187 variants in human PAH protein. The rationale of this study is based on our hypothesis and previous findings that the harmful variants are more likely to occur at randomly unpredictable amino acid pairs rather than at randomly predictable pairs. This is reasonable to argue as randomly predictable amino acid pairs are less likely to be deliberately evolved, whereas randomly unpredictable amino acid pairs are probably deliberately evolved in connection with protein function. 94.12% of 187 variants occurred at randomly unpredictable amino acid pairs, which accounted for 71.84% of 451 amino acid pairs in human PAH protein. The chance of a variant occurring is five times higher in randomly unpredictable amino acid pairs than in predictable pairs. Thus, randomly unpredictable amino acid pairs are more sensitive to variance in human PAH protein. The results also suggest that the human PAH protein has a natural tendency towards variants.     

Multiplicity of the Amino Acid Permeases in Saccharomyces cerevisiae IV. Evidence for a General Amino Acid Permease

Kinetic and genetic evidences are presented to show that, in addition to specific amino acid permeases, Saccharomyces cerevisiae has a general amino acid permease which catalyzes the transport of basic and neutral amino acids, but most probably not that of proline. The general amino acid permease appears to be constitutive, and its activity is inhibited when ammonium ions are added to the culture medium. A mutant which has lost the general amino acid permease activity was isolated. Its mutation, named gap (general amino acid permease), is not allelic to the aap (amino acid permease) mutation of Surdin et al., which has a quite different phenotype and cannot be considered as having selectively lost the general amino acid permease activity.     

不同来源仙草的氨基酸比较分析

采用盐酸水解法分析不同来源仙草的氨基酸组成及含量差异,结果表明供试仙草均含有17种氨基酸和7种必需氨基酸,氨基酸总量为4.75％～13.65％,17种氨基酸总量和7种必需氨基酸总量的高低顺序都是9＞10＞5＞8＞1 ＞6＞4＞3＞2＞7,均以9号仙草含量最高,7号仙草最低.各种氨基酸含量高低顺序相似,以谷氨酸、天门冬氨...     

MEASUREMENTS OF RATES OF PROTEIN SYNTHESIS IN RAT BRAIN SLICES

The use of tracer concentrations of labelled amino acids to measure incorporation in incubated slices of brain results in wide fluctuations with time in the specific activity of the precursor. Using concentrations of about 1 mm of labelled amino acid facilitates the accurate measurement of rates of synthesis. These higher precursor levels in the medium decrease the fluctuations in free amino acid specific activity due to dilution by endogenous amino acid and the production of amino acid by protein degradation, and decrease the lag in incorporation due to transport phenomena. Concentrations of 1 mm amino acid in the medium did not inhibit protein synthesis; with valine, leucine, phenylalanine, lysine and histidine, incorporation rates were similar when measured at trace concentrations and at 1 mm medium levels. The source of amino acid for protein synthesis appears to be intracellular. No evidence could be found for the preferential use of extracellular medium amino acid. The rate of incorporation of amino acids in incubated slices of rat brain was 0.087 per cent of the protein amino acid/h.     

Substrate-dependent regulation of intracellular amino acid concentrations in cultured bovine aortic endothelial cells

Amino acid deprivation induces adaptive changes in amino acid transport and the intracellular amino acid pool in cultured cells. In this study intracellular amino acid levels were determined in cultured bovine aortic endothelial cells (EC) deprived of L-arginine or total amino acids for 1, 3, 6 and 24 h. Amino acid concentrations were analyzed by reverse phase HPLC after precolumn derivatisation. Under normal culture conditions levels of L-arginine L-citrulline, total essential and non-essential amino acids were 840 +/- 90 microM, 150 +/- 40 microM, 11.4 +/- 0.9 mM and 53.3 +/- 3.4 mM (n = 9), respectively. In EC deprived of L-arginine or all amino acids for 24 h L-arginine and L-citrulline levels were 200 microM and 50 microM, and 670 microM and 100 microM Deprivation of L-arginine or total amino acids induced rapid (1 h) decreases (30 - 50%) in the levels of other cationic (lysine, ornithine) and essential branched-chain (valine, isoleucine, leucine) and aromatic (phenylalanine, tryptophan) amino acids. L-glutamine was reduced markedly in EC deprived of total amino acids for 1 h - 6 h but actually increased 3-fold in EC deprived of L-arginine for 6 h or 24 h. Arginine deprivation resulted in a rapid decrease in the total intracellular amino acid pool, however concentrations were restored after 24 h. Increased amino acid transport and/or reduced protein synthesis may account for the restoration of amino acid levels in EC deprived of L-arginine. The sustained reduction in the free amino acid pool of EC deprived of all amino acids may reflect utilization of intracellular amino acids for protein synthesis.     

氨基酸转运体在肿瘤代谢中的研究进展

代谢重编程是肿瘤的重要特征,是指肿瘤细胞为满足其快速增殖的生物合成与能量需求,对其糖代谢、脂代谢以及氨基酸代谢等代谢路径进行的重编程,以维持增长速度以及补偿能量代谢所造成的氧化还原压力。虽然不同的癌症代谢变化不同,但有些特征是所有癌症共有的,氨基酸代谢重编程是其中一个重要的特征。氨基酸进出细胞需要氨基酸转运体的协助,因而在肿瘤细胞中多种特定的氨基酸转运体均过表达。靶向氨基酸转运体通过影响肿瘤细胞的氨基酸代谢从而达到抗肿瘤的目的,是目前抗肿瘤药物的研究热点之一。主要介绍了几种在肿瘤代谢中发挥重要作用的氨基酸转运体以及靶向氨基酸转运体抗肿瘤治疗的研究进展及相关作用机制,旨在了解氨基酸转运体在抗肿瘤研究中的作用,以期促进靶向氨基酸转运体抗肿瘤药物的发展。     

闽产李果实氨基酸组成及其营养分析

为了弄清不同闽产李（Prunus salicina）果实氨基酸含量、组成及营养价值,采用氨基酸自动分析仪 对不同李果实样品中各种氨基酸的含量进行检测,并对其组成进行比较分析。结果表明,李果实含有18种蛋白质氨基酸和3种非蛋白质氨基酸。田黄李的牛磺酸含量与蛋白质氨基酸含量均最高分别为26.54 mg/100 g和496.14 mg/100 g;皇后李的鸟氨酸、药用氨基酸、酸味氨基酸含量以及特殊功效蛋白质氨基酸的比重均最高分别为0.36 mg/100 g、364.67 mg/100 g、298.28 mg/100 g和73.45%;早熟胭脂李的γ-氨基丁酸含量最高为7.98 mg/100 g;大胭脂李的支链氨基酸含量最高为46.77 mg/100 g。李果实中氨基酸种类齐全、含量存在一定的差异,可根据不同的开发利用目标选择合适的品种。     

不同产地蜂胶中氨基酸含量的比较

选择国内外7种不同产地蜂胶,采用氨基酸自动分析仪分别测定其氨基酸含量。结果表明,所测蜂胶均含有17种以上氨基酸,其构成模式比较接近,但氨基酸含量差异较大,北京蜂胶总氨基酸含量最低,为26.96mg·100g-1,杭州蜂胶总氨基酸含量最高,为165.74mg·100g-1,谷氨酸为各产地蜂胶中含量最高的氨基酸,其中杭州蜂胶谷氨酸含量居首,为30.74mg·100g-1,大部分蜂胶中约30%的氨基酸为必需氨基酸。不同产地蜂胶氨基酸含量差异,可能是影响其生物活性的一个重要因素。     

板蓝根热加工过程中氨基酸组分分析

利用氨基酸自动分析仪对板蓝根的新鲜植物组织和不同加工程度的板蓝根药材中的总氨基酸和游离氨基酸含量进行测定。结果表明:板蓝根的新鲜植物组织和不同加工程度的板蓝根药材氨基酸在含量上有明显差别。结论为:不同加工程度的板蓝根药材中氨基酸含量差别明显,其中碱性氨基酸含量的差别尤其显著,该差异可能是由于加工过程中发生美拉德反应造成的。