共查询到20条相似文献，搜索用时 31 毫秒
1.
多肽和蛋白质的人工合成,就是多个氨基酸在一定的条件下通过肽键形成多肽链。氨基酸是合成多肽和蛋白质的原料。在合成前各个氨基酸都必须经过基团保护、氨基和羧基的活化处理,然后经接肽,去除保护基,最后形成多肽链。本文对目前国内外常用的液相合成法和固相合成法的原理和步骤进行了简要的评述。 相似文献
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为探究槟榔中的生物活性成分,本研究以不同组织的槟榔为材料,利用高效液相色谱?质谱联用技术进行了非靶向代谢组学检测,经过定性分析,共获得了158个代谢物（包括氨基酸、脂质、核苷酸、生物碱和类黄酮等物质）,首次在槟榔中发现槟榔次碱己糖苷的存在,并对氨基酸和生物碱进行了相对定量,发现芳香族氨基酸和支链氨基酸主要分布在种子中;烟酸衍生物在叶片中含量较高,槟榔次碱己糖苷和去甲基槟榔碱在外果皮中含量较高,其余生物碱均显示出在果实中尤其是种子中有较多的积累。基于烟酸、葫芦巴碱和槟榔碱的结构相似性,推测槟榔碱的合成通路是以天冬氨酸为起点,以烟酸、葫芦巴碱为基本骨架进行合成的。 相似文献
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Chain initiation and control of protein synthesis 总被引：15，自引：0，他引：15
H Noll 《Science (New York, N.Y.)》1966,151(715):1241-1245
Analysis of the enzymatic mechanism of chain extension during protein synthesis and studies with N-formylmethionyl-sRNA suggest that chain initiation requires formylation of the amino group of the amino acid destined to start chain growth. The existence of a set of starting triplets coding for a special set of N-formylaminoacyl-sRNA's is postulated. These triplets might be ambiguous in the sense that they specify different amino acids, depending on whether they are at the beginning of or within a message. A number of starting triplets and their NH(2)-terminal amino acids are predicted from previously suggested ambiguities. The biochenmical, regulatory, and genetic implications of a formylation step controlling chain initiation are discussed. 相似文献
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仔猪肠道发育和氨基酸营养调控机制 总被引：2，自引：0，他引：2
肠道生长是仔猪生长发育的核心和快速生长的基础。新生仔猪肠道发育不健全,断奶引起肠黏膜结构和功能变化,导致绒毛萎缩、通透性增加、消化吸收和屏障功能受损。氨基酸是小肠优先利用的重要营养物质,通过转运载体进入肠上皮细胞内作用于相应的受体,启动细胞信号,调控细胞内生理过程。氨基酸作为肠黏膜主要能量来源以及合成蛋白质和多种信号分子的前体物,对促进肠道生长发育、维持肠道结构功能具有重要作用。本文围绕仔猪肠道发育和氨基酸利用,揭示猪肠黏膜形态结构发育和断奶适应性变化规律,阐明猪肠道氨基酸感应利用机制以及氨基酸促进仔猪肠道结构功能发育的作用机制,为调控肠道氨基酸代谢、提高饲料氨基酸利用效率提供了理论基础,对促进仔猪肠道健康、提高生产效率具有重要的科学意义。 相似文献
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对野生型TMV—U1的外壳蛋白羧端进行缺失突变,观察到外壳蛋白羧端序列缺失4个氨基酸（即外壳蛋白保留154个氨基酸）的TMV154TAG能较强地系统侵染烟草,并高水平表达外壳蛋白,经过二次转接新烟草植株仍保持较强的系统侵染状况,复制完整病毒粒子。结果说明外壳蛋白羧端序列4个氨基酸序列的缺失对烟草花叶病毒感染和复制无严重影响,对利用外壳蛋白羧端缺失型病毒载体表达外源多肽技术具有一定的应用价值。 相似文献
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Antimalarials: effects on in vivo and in vitro protein synthesis 总被引：2，自引：0，他引：2
The antimalarials quinine, chloroquine, primaquine, and quinacrine inhibited the uptake and incorporation of amino acids in vivo, but these drugs had considerably less effect on cell-free protein synthesis. The results indicate that the primary effect of the four drugs on protein synthesis is blocking of amino acid uptake by the cells. 相似文献
8.
Regulation of bacterial growth 总被引：5，自引：0，他引：5
D P Nierlich 《Science (New York, N.Y.)》1974,184(4141):1043-1050
Is the control of bacterial metabolism so complex? The answer can be found in a simple experiment. Two cultures of bacteria are grown in different mediums. One contains as the carbon and nitrogen sources a mixture of amino acids, while the other contains only glucose and ammonia, so that the cells must synthesize all of the amino acids. The results show that insofar as the cells in both cultures grow at comparable rates, they will have the same composition in terms of DNA, RNA, and protein (30). To explain this phenomena I have argued that through the control mechanisms responsible for the distribution of substrates in intermediary metabolism, the substrates of protein synthesis are produced at concentrations and rates commensurate with the ability of the environment to support growth. The provision of these substrates relative to the ability of the protein forming system to utilize them regulates the synthesis of ribosomal and transfer RNA, which, after adjustment for various modulating influences, such as nonfunctioning ribosomes or ribosomal RNA turnover, brings the number of functioning ribosomes to a point in keeping with the provision of external nutrients. The synthesis of messenger (or total) RNA, ribosomal proteins, and DNA, and the process of cell division, for example, are subject to their own controls, but through the burden they each place on intermediary metabolism, they provide a means for partitioning the cell's metabolic resources. It might be noted that this view may not be very far from the idea once held that the rate at which each of the transfer RNA's was changed by amino acids regulate the synthesis of bacterial RNA, but growth regulation is clearly more complicated than implied by that model (76). 相似文献
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Freeze-fracture of Acholeplasma laidlawii membranes from cells incubated in the presence of puromycin or omission of amino acids reveals a decrease in the number of particles between 50 and 100 angstroms in the hydrophobic fracture plane, which strongly suggests that these particles are protein. Additional evidence indicates that they may be involved in substrate transport. 相似文献
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[目的]通过基因工程手段改良酿酒酵母菌以提高谷胱甘肽的产量。[方法]利用基因重组技术分别构建CYS3基因剔除菌和CYS4基因剔除菌,对比了野生菌与突变酵母菌的生长曲线,并定量检测2者中谷胱甘肽和氨基酸的含量,得出CYS3基因和CYS4基因剔除对谷胱甘肽和氨基酸代谢的影响程度。[结果]与野生菌株相比,CYS3基因剔除菌中谷胱甘肽含量降低了26.1%,CYS4基因剔除菌中谷胱甘肽含量提高了6.0%。[结论]综合CYS3和CYS4基因剔除和其他在谷胱甘肽代谢途径中关键酶基因剔除试验结果所得数据,可以建立酿酒酵母谷胱甘肽代谢网络系统生物学模型。 相似文献
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Amino acids are produced under possible primitive Earth conditions by irradiation of gas mixtures with long-wavelength ultraviolet light, representing the most abundant useful energy source for prebiological organic synthesis. Hydrogen sulfide is the initial photon acceptor in this work; superthermal atomic hydrogen photodissociation products appear to initiate reactions leading to amino acid synthesis with an overall quantum yield on the order of 5X10(-5). 相似文献
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Tryptophan deficiency in rabbit reticulocytes: polyribosomes during interrupted growth of hemoglobin chains 总被引：9，自引：0，他引：9
Of several amino acids essential for optimum hemoglobin synthesis by the rabbit reticulocyte, only omission of tryptophan results in polyribosome disaggregation. This disaggregation is prevented by the omission of both tryptophan and an amino acid that is relatively more essential than tryptophan for hemoglobin synthesis. Since tryptophan is located only near the amino-terminal ends of both chains of rabbit globin, the results indicate that single ribosomes and those in polyribosomes are in a dynamic state in the intact cell. 相似文献
13.
KEELER RF 《Science (New York, N.Y.)》1959,129(3363):1617-1618
Proteins, certain amino acids, and amines undergo a potentially useful color reaction. The reaction involves the apparent formation of pyrroles when the compounds are allowed to react with acetonylacetone. The pyrroles yield colored complexes on coupling with p-dimethylaminobenzaldehyde. This report describes the specificity and possible uses of this reaction in colorimetric measurements and in paper chromatographic detection of these compounds. 相似文献
14.
含S氨基酸对肉仔鸡解毒作用的研究 总被引：3，自引：0，他引：3
通过向饲料中添加黄曲霉毒素（AF）和两种含S氨基酸－蛋氨酸及半胱氨酸，根据生化指标的测定情况，研究蛋氨酸及半胱氨酸对雏鸡黄曲霉毒素中毒的解毒作用。结果表明：口服AF组肉仔鸡白细胞数目及血清GPT水平明显升高，而红细胞数目以及肝脏GSH水平和肝脏DNA合成量减少。补加蛋氨酸或半胱氨酸则可减轻AF对雏鸡肝脏的损伤，使上述各指标均与对照组无明显差异。 相似文献
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Narita M Young AR Arakawa S Samarajiwa SA Nakashima T Yoshida S Hong S Berry LS Reichelt S Ferreira M Tavaré S Inoki K Shimizu S Narita M 《Science (New York, N.Y.)》2011,332(6032):966-970
Protein synthesis and autophagic degradation are regulated in an opposite manner by mammalian target of rapamycin (mTOR), whereas under certain conditions it would be beneficial if they occurred in unison to handle rapid protein turnover. We observed a distinct cellular compartment at the trans side of the Golgi apparatus, the TOR-autophagy spatial coupling compartment (TASCC), where (auto)lysosomes and mTOR accumulated during Ras-induced senescence. mTOR recruitment to the TASCC was amino acid- and Rag guanosine triphosphatase-dependent, and disruption of mTOR localization to the TASCC suppressed interleukin-6/8 synthesis. TASCC formation was observed during macrophage differentiation and in glomerular podocytes; both displayed increased protein secretion. The spatial coupling of cells' catabolic and anabolic machinery could augment their respective functions and facilitate the mass synthesis of secretory proteins. 相似文献
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水稻根系形态生理与产量、品质形成及养分吸收利用的关系 总被引：51，自引：5，他引：46
植物根系既是水分和养分吸收的主要器官,又是多种激素、有机酸和氨基酸合成的重要场所,其形态和生理特性与地上部的生长发育有密切联系.本文综述了水稻根系形态生理与产量形成及水分养分吸收利用的关系,介绍了根系化学信号(激素、有机酸等)对稻米品质形成的作用及根尖细胞超微结构与地上部生长发育关系的最新研究进展,讨论了水稻根系研究存... 相似文献
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Xiao-feng YUE Yan-lun JU Zi-zhu TANG Ya-meng ZHAO Xu-liang JIAO Zhen-wen ZHANG 《农业科学学报》2019,18(9):2052-2062
The effects of the severity and timing of leaf removal(LR) on the amino acids of Sauvignon Blanc grapes and wines were studied during the 2017 growing season. High-performance liquid chromatography(HPLC) was used to analyze the amino acids profiles of grape berries and wines. The basal leaves were removed at three time points(40, 56 and 72 days after flowering, named LR40, LR56 and LR72, respectively) at two severity levels(one at which the first, third, and fifth basal leaves of each shoot were removed(50% level); and another at which the first six basal leaves were removed(100% level)). The results showed that leaf removal had little impact on total soluble solids(°Brix), titratable acidity, pH or berry weight. The LR72-50% treated grapes had higher berry weight, titratable acidity and °Brix than those of the other treatments. The highest concentrations of total amino acids and of total amino acids except proline were detected in LR72-50% treated grapes(2 952.58 and 2 764.36 mg L~(-1), respectively); the lowest were detected in LR72-100% treated grapes(2 172.82 and 2 038.71 mg L~(-1), respectively). LR72-50% treatment significantly promoted the synthesis of aspartic acid, serine, arginine, alanine, aminobutyric acid and proline at both severity levels for grapes, the concentrations of all of these amino acids were increased relative to the control concentrations. The LR72-50%, LR40-100% and LR72-100% treated wines had higher total amino acids concentrations and higher concentrations of some individual amino acids, such as arginine, alanine and serine, than did the control wines. Of all the amino acids studied, glycine, tyrosine, cysteine, methionine and lysine were not significantly influenced by the timing or severity basal defoliation in grapes and wines. The present study reveals the effects of the timing and severity of leaf removal on the amino acids profiles of grapes and wines. 相似文献
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小麦耐受C_d胁迫的生理生化机制探讨 总被引：1，自引：0，他引：1
对比研究了6个耐Cd性不同的小麦品种对Cd的吸收、累积量、在细胞各组分的分布、几种酶活性及氨基酸含量的变化。结果表明，耐性小麦品种体内SOD、CAT及POD的活性可得以维持或提高，氨基酸合成加速，游离脯氨酸累积量增加，为其耐受Cd胁迫提供了物质基础。 相似文献
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肽是分子结构介于氨基酸和蛋白质之间的一类化合物,含2或3个氨基酸残基的为小肽。小肽可能存在3种转运系统。反刍动物吸收肽的主要部位是瓣胃。小肽本身的理化性质、动物生理状态、日粮蛋白和采食水平等影响小肽的吸收。小肽可避免氨基酸间的吸收竞争,促进氨基酸的吸收,加速蛋白质的合成,促进肠道黏膜结构和功能发育,刺激消化酶的分泌和活性的提高,改善提高生产性能。对小肽的吸收机制及营养功能进行了综述。 相似文献