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.     

诺丽果与热带水果中氨基酸含量及组成对比分析

以诺丽果和16种海南常见热带水果为材料,对比分析了氨基酸含量及组成。结果表明:诺丽果含有18种氨基酸,种类齐全。其氨基酸总量、人体必需氨基酸含量和儿童必需氨基酸含量均居第1位。诺丽果的E/T值为37.13%,E/N值为0.59,符合理想蛋白质的要求。诺丽果中各种人体必需氨基酸,Val、Ile、Leu、Phe+Tyr、M et+Cys、Thr的含量占氨基酸总量的比例,与1973年FAO/WHO修订的人体必需氨基酸含量模式谱基本一致,仅Lys中度缺乏。诺丽果中鲜味类、芳香族、甜味类氨基酸含量居第1位。     

On the antisymmetry of the amino acid code table

Antisymmetry of the amino acid code table in terms of codon degeneracy is pointed out, and it is related to a physico-chemical problem of codon-anticodon interaction energy. A strong negative correlation between molecular weight of an amino acid and its codon degeneracy is pointed out, and its implication to the origin of the amino acid code table is discussed. Finally, an earlier form of the amino acid code table is proposed.     

鱼腥草种质资源氨基酸组成及含量分析

分别对鱼腥草16个不同居群幼嫩地上和地下部分的氨基酸成分进行高效液相色谱分析。结果发现,鱼腥草不同居群的氨基酸含量不尽相同,同一居群幼嫩地上茎叶和地下茎的氨基酸含量也有差异,多以地上茎叶高于地下茎。在分析的17种氨基酸中,所有居群均含有16种氨基酸,都不含Cys-SS-Cys。地上部分氨基酸中Glu含量最高,His含量最低;地下部分氨基酸中Glu含量最高,Tyr含量最低。地上部分氨基酸总量以W01-16为最高,而地下部分氨基酸总量以W01-99为最高,分别为27.89mg/g和15.46mg/g。蕺菜与峨眉蕺菜间氨基酸成分间无显著差别。鱼腥草种质资源氨基酸含量与染色体数目间相关不显著。     

Amino acid exchange mechanism in the basolateral membrane of the midgut epithelium from the larva ofHyalophora cecropia

Summary It is concluded that the amino acid, -aminoisobutyric acid, is taken up from the blood into the midgut epithelium by an exchange mechanism for the following reasons: 1. The amino acid uptake becomes saturated with increasing amino acid concentration on the blood side; 2. The amino acid in the tissue cannot be washed out again to the blood side unless an amino acid is present in the blood side bathing solution; 3. The uptake mechanism is independent of metabolism. This amino acid exchange mechanism is independent of the active transport of potassium from blood side to lumen side, the exchange of potassium between blood and midgut tissue, and the transport of the amino acid, -aminoisobutyric acid, across the midgut epithelium from lumen to blood.     

Amino acid metabolism and the energetics of growth

The nonessential amino acids are involved in a large number of functions that are not directly associated with protein synthesis. Recent studies using a combination of transorgan balance and stable isotopic tracers have demonstrated that a substantial portion of the extra‐splanchnic flux of glutamate, glutamine, glycine and cysteine derives from tissue synthesis. A key amino acid in this respect is glutamic acid. Little glutamic acid of dietary origin escapes metabolism in the small intestinal mucosa. Furthermore, because glutamic acid is the only amino acid that can be synthesized by mammals by reductive amination of a ketoacid, it is the ultimate nitrogen donor for the synthesis of other nonessential amino acids. Because the synthesis of glutamic acid and its product glutamine involve the expenditure of adenosine triphosphate (ATP), it seems possible that nonessential amino acid synthesis might have a significant bearing on the energetics of protein synthesis and, hence, of protein deposition. This paper discusses the topic of the energy cost of protein deposition, considers the metabolic physiology of amino acid oxidation and nonessential amino acid synthesis, and attempts to combine the information to speculate on the overall impact of amino acid metabolism on the energy exchanges of animals.     

Conservation of the basic pattern of cellular amino acid composition of archaeobacteria during biological evolution and the putative amino acid composition of primitive life forms

Summary. Previous studies showed that the cellular amino acid composition obtained by amino acid analysis of whole cells, differs such as eubacteria, protozoa, fungi and mammalian cells. These results suggest that the difference in the cellular amino acid composition reflects biological changes as the result of evolution. However, the basic pattern of cellular amino acid composition was relatively constant in all organisms examined. In the present study, we examined archaeobacteria, because they are considered important in understanding the relationship between biological evolution and cellular amino acid composition. The cellular amino acid compositions of Archaeoglobus fulgidus, Pyrococcus horikoshii, Methanobacterium thermoautotrophicum and Methanococcus jannaschii differed slightly from each other, but were similar to those determined from codon usage data, based on the complete genomes. Thus, the cellular amino acid composition reflects biological evolution. We suggest that primitive forms of life appearing on earth at the end of prebiotic evolution had a similar-cellular amino acid composition. Received November 28, 2000 Accepted January 30, 2001     

Control of amino acid transport in the mammary gland of the pregnant mouse

The regulation of the uptake of the amino acid analog α-aminoisobutyric acid was studied in diced mammary glands from pregnant mice. Stimulation of uptake by insulin was not prevented by inhibitors of protein synthesis; protein synthesis inhibitors decreased uptake by 20%; this response occurred more promptly in insulintreated tissues. Elimination of extracellular amino acids led to a substantial increase in transport which was not abolished by inhibitors of protein synthesis. These results indicate that insulin does not increase amino acid transport in this system by altering synthesis and degradation of transport protein. They are consistent with a model in which the activity of the existing amino acid transport protein is subject to negative feedback regulation from the intracellular amino acid pool.     

人胃癌组织及胃正常组织氨基酸差异研究

对 2 2例胃癌组织及其癌边组织、胃正常组织氨基酸进行了测定。发现胃癌组织氨基酸总量低于癌边组织氨基酸总量 ,癌边组织氨基酸总量又低于胃正常组织氨基酸总量。癌中组织与癌边组织相比有 8种氨基酸明显降低 ,P <0 .0 1 ;其中三种为人体必需氨基酸 ,三种为生糖氨基酸。胃癌组织与胃正常组织相比 3种生糖氨基酸明显降低 ,P<0 .0 5。结果表明 :胃癌组织存在明显的氨基酸代谢异常     

Amino acid composition of aragonitic concholin in the shell of Arctica islandica

Haugen, J. E. & Sejrup, H. P. 1990 04 15: Amino acid composition of aragonitic conchiolin in the shell of Arctica islandica. Lethaia , Vol. 23, pp. 133–141. Oslo. ISSN 0024–1164.
The distribution of amino acids within the two aragonitic shell layers of modern specimens of the mollusc Arctica islandica (Linné) has been studied in detail. The mean total hydrolyzed amino acid content was 19 nmol*mg in the inner layer and 15 nmol/mg in the outer layer. No significant difference in amino acid composition could be found between the two layers. The layers contained minor amounts of free amino acids which made up 0.3–0.7% of the total hydrolyzed amino acid content. The composition of the free amino acid fraction was very similar in each of the two layers, but differed somewhat from the total hydrolyzed fraction. The total hydrolyzed fraction was dominated by aspartic acid, glycine. alanine and glutamic acid, which together made up 62% of the total amount of amino acids, whereas the free fraction was dominated by Asp. Ser, Gly and Tyr. Amino acid content and composition within a single layer showed little variation from umbo to the ventral margin. The amino acid composition is in accordance with previously reported data on similar mineral structures which support the theory of structure specific rather than species specific amino acid composition. * Arctica islandica. amino acids. shell structure .     

Optimizing the protein nutrition of growing-finishing pigs

Growing-finishing pigs should consume each day the minimum amounts of energy and amino acids needed for maximum lean deposition. This should optimize performance traits, carcass leanness, and N excretion. These ideal conditions are difficult to achieve under experimental or farm conditions due to the factors affecting amino acid requirements and feed intake on a daily basis. Lean deposition rate and sex are two of the major factors affecting amino acid needs. If possible, maximum lean deposition rates should be determined for each herd in order to customize feeding programs, and split-sex feeding will improve N utilization.

Amino acid requirements have been determined empirically and by the factorial method. The latter is preferred if the efficiency of use of absorbed amino acids can be accurately determined. Development of computer models will likely be needed to accomplish this. Apparent ileal digestibility of amino acids is the most practical means of estimating amino acid absorption at present, although it likely overestimates amino acid availability for some amino acids.

Crystalline amino acids can be used to improve amino acid balance and reduce excessive intake of protein which should improve feed efficiency. A portion of the high-quality protein feeds in pig diets can be replaced by synthetic amino acids without sacrificing performance, but the effects of these substitutions on carcass merit is uncertain.

Excretion of N, and the concomitant reduction of N in manure that has to be disposed of, can be manipulated nutritionally by increased use of crystalline amino acids to lower dietary protein, by use of highly digestible feedstuffs and by precise matching of amino acid needs to amino acid supply. Use of these factors could lead to a reduction in total N wastes of 20–30%.     

Free amino acid pools in some tissues of the pregnant rat

Plasma amino acid pools show important variations throughout the gestational period in the rat, with decreased values at mid-pregnancy and recovered levels before parturition. This decrease in amino acid levels at mid-pregnancy is mainly due to changes in the gluconeogenic amino acid group. During pregnancy, whole tissue amino acid pools increase in the liver but no changes appear in other studied tissues. However, individual gluconeogenic amino acid concentrations change significantly in skeletal muscle, skin and liver through the gestational period. Pregnancy may be understood as a challenge to the mother's metabolism but the pattern of tissue amino acid changes is not similar to that found in some stressant situations and it should be the net consequence of maternal adaptations to the increased metabolic needs.     

红菜薹6个品种氨基酸含量的分析比较

对红菜薹6个品种的氨基酸种类、含量进行分析测定,结果表明,红菜薹含有17种氨基酸,其中7种为人体必需氨基酸,各品种间各类氨基酸含量差异不显著;相对于茎干而言,红菜薹的薹叶具有更高的营养价值和药用价值;不同的采收温度对各类氨基酸含量的影响不同。     

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。     

炒焦对山楂中氨基酸含量的影响分析

为探索炒焦对山楂中氨基酸的影响及山楂炒焦过程中氨基酸的变化,对炒焦前后山楂中氨基酸含量的变化进行了分析.测定结果显示,炒焦前后山楂中氨基酸的种类不变,各种氨基酸含量变化不一;方差分析显示炒焦前后氨基酸的含量变化不显著,炒焦对山楂中氨基酸的影响较小.由于山楂在炒焦过程具备发生美拉德反应的物质基础和客观条件,推测山楂中的氨...     

Impact of the C-N status on the amino acid profile in tobacco source leaves

This paper investigates the influence of the carbon (C) and nitrogen (N) status on the amino acid profile in tobacco source leaves. Treatments used included growing plants at different light intensities, using an antisense RBCS (small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase) construct to inhibit Rubisco activity, growing plants on 12 or 0.5 mM nitrate, comparing wild-types with genotypes that have small and large decreases in nitrate reductase (NIA) activity, and sampling plants at different times during the diurnal cycle. This combination of experiments provides information on how amino acid levels respond to several inputs including the C and N status, nitrate, excess light and light-dark transitions. The data set was analysed using principal component analysis, regression analysis and by normalizing the level of each individual amino acid on the total amino acid pool. Most amino acids show a downward trend when the C or the N status is decreased, and rise during day and fall at night during the diurnal cycle. However, individual amino acids often showed deviating responses. Furthermore, no evidence was found for feedback inhibition of minor amino acid synthesis, either within or between pathways, when 18 individual amino acids were supplied to detached leaves. Results indicate that regulation of amino acid metabolism, for example by the C and N status, leads to qualitatively similar responses of many amino acids, but homeostatic mechanisms involving feedback inhibition within or between individual amino acid biosynthesis pathways are not stringent. All of the above inputs affect the level of phenylalanine, an amino acid that is also the substrate for an important sector of secondary metabolism. The levels of glutamate were remarkably constant, indicating that unknown mechanisms stabilize the concentration of this key central amino acid. Analyses of metabolite levels and feeding experiments indicated that 2-oxoglutarate plays an important role in regulating glutamate levels. Glutamate was the most effective inhibitor of NIA activity when 18 individual amino acids were supplied to detached leaves. Feeding glutamate, and other downstream amino acids, led to an increase of glutamine, indicating glutamate exerts feedback regulation on ammonium metabolism.     

Determination of the amino acid sequence of adreno-ferredoxin from sheep adrenocortical mitochondria.

1. An adreno-ferredoxin was purified from sheep adrenocortical mitochondria. 2. Its amino acid composition and amino acid sequence were determined chemically. 3. It was found to be composed of 127 amino acid residues, including two tyrosyl residues. 4. The amino acid sequences of various ferredoxins of the two iron and two sulfur type were compared with respect to amino acid homology.     

Infusion of amino acids decreases the hyperglycaemic effect of per- and postoperative glucose infusion: an experimental study in the rabbit

The effects on blood glucose concentration of 10% glucose with amino acid solution at low (18%) and high (25%) concentration of branched chain amino acids were studied, two days after laparotomy in fasted rabbits. During the whole study period, saline infusion was associated with normoglycaemia. Among the other infusion combinations peroperative infusion of amino acid solution high in branched chain amino acids with 10% glucose was the least hyperglycaemic. An amino acid solution low in branched chain amino acids with 10% glucose had the lowest hyperglycaemic effect 24 hours postoperatively. After 48 hours an infusion of 10% glucose produced the weakest hyperglycaemia. In preoperatively and 24 hours postoperatively 10% glucose was more hyperglycaemic than 10% glucose with the two amino acid solutions. After 24 and 48 hours, infusion of 10% glucose with amino acids high in branched chain amino acids was more hyperglycaemic than 10% glucose with amino acids low in branched chain amino acids.     

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.