花馔及其氨基酸营养

应用日立835 50型高效氨基酸自动分析仪,对十五种常见食用花卉干样进行了水解蛋白氢基酸成分测定,结果发现:①花馔中酸水解蛋白氨的基酸种类齐全,总氨基酸含量较高,占食用干物质的6.00—29.45％。②花馔中人体必需氨基酸含量丰富,占总氨基酸含量的29.50—42.60％。尤以亮氨酸、苯丙氨酸、赖氨酸和苏氨酸含量为高。③花馔中甜、鲜类氨基酸含量也较高,分别占总氨基酸的25.94—39.89％,23.35—33.38％,花馔是兼有营养、颜色、美味的天然食物,值得人类利用。     

山东名优特产水果氨基酸及其营养成分的研究

本文研究测定了１７种山东省名优特产水果的蛋白质、氨基酸及其它营养成分的组成。证明这些水果不仅口味美,而且有较好的营养成分构成。     

双孢蘑菇菇脚氨基酸含量的测定及营养评价

测定了双孢蘑菇菇脚中蛋白质和氨基酸的含量,应用模糊识别法和氨基酸比值系数法,以鸡蛋蛋白为标准蛋白,以WHO/FAO的必需氨基酸参考模式为评价标准,对双孢蘑菇菇脚的蛋白质营养价值进行了全面评价,并与双孢蘑菇子实体的蛋白质进行比较.结果表明:双孢蘑菇菇脚蛋白质中总氨基酸含量为73.16％,氨基酸种类齐全,必需氨基酸含量占氨...     

小肽在猪营养中的研究

蛋白质在消化道中的消化终产物往往大部分是小肽而非游离氨基酸,小肽能完整地被吸收并以二、三肽形式进入血液循环,小肽在蛋白质营养中有着重要的作用。动物为了达到最佳生产性能,必须需要一定数量的小肽,作者就目前国内、外对小肽在猪营养中的研究及应用现状作一综述。随着蛋白质和氨基酸营养研究的深入,人们已逐渐认识到肽营养的重要性。Aga r(1953)观察到,肠道能够完整转运双甘肽。其后Naey(1959)和Smith(1960)首先提出肽可被完全转运的确切证据。最简单的肽是由2个氨基酸组成的二肽,其中含有1个肽键。含有3、4、5个等氨基酸的肽分别被称为三、四、五肽等。由2--10个氨基酸通过     

野苋菜的氨基酸含量与营养评价

野苋菜含有１８种氨基酸,其中有营养必需的８种氨基酸。含硫氨基酸ＡＡＳ＝０．５１,为第一限制氨基酸。Ｅ／Ｅ＋Ｎ＝４１．６％,Ｅ／Ｎ＝０．７１,接近ＷＨＯ／ＦＡＯ提出的参考蛋白模式。     

不同水分条件下春小麦种群中个体大小不整齐性及遗传学分析不同水分条件下春小麦种群中个体大小不整齐性及遗传学分析

 种群内个体大小不整齐性是种群数量结构的主要指标。本文研究了不同水分条件下,3个品种春小麦种群个体大小不整齐性的建立及变化规律。对春小麦种群不整齐性的遗传学分析表明：遗传结构与随机环境修饰对种群数量结构形成的相对重要性,因水分条件不同而异。种群不整齐性在自然选择中的作用可用下列简单模型表示：CSo＝SH×hSH2 CSo：自然选择强度;SH：大小不整齐性;hSH2：不整齐性的遗传力。     

脑源性神经营养因子研究进展

脑源性神经营养因子是一种小分子二聚体蛋白质,在结构上与神经生长因子相关。对中枢神经系统的多种类型神经元的生长、发育、分化、维护和再生部具有重要作用,对于治疗运动神经元病变以及神经系统迟行性疾病有显疗效。本对其细胞与分子生物学特征、生物学功能进行阐述。     

鼠曲草的氨基酸含量的测定及营养评价

用氨基酸分析仪测定了鼠曲草中各种氨基酸的组成,并对其进行营养评价。结果表明,鼠曲草样品(茎、花)经酸水解 处理,含有苏氨酸、缬氨酸、蛋氨酸、苯丙氨酸、异亮氨酸、亮氨酸和赖氨酸等17种氨基酸,茎中总氨基酸质量分数为18.25%、花 中为14.44%;其中包含人体必需的8种氨基酸,配比合理:E/(E+N)=0.38(茎)或0.37(花),E/N=0.62(茎)或0.59(花), 与WHO/FAO提出的E/(E+N)应为0.4左右,E/N应为0.6左右的参考蛋白质模式接近,说明鼠曲草在医学和营养学上都 有很高的研究价值,值得大力开发利用。     

橄榄蚶软体部营养成分分析与评价

测定了橄榄蚶(EsteUarca olivacea)软体部的基本生化成分、氨基酸和脂肪酸的含量.结果表明,橄榄蚶软体部含水量为81.36%,粗蛋白、粗脂肪、总糖和灰分分别占软体部干重的63.64%、10.95%、13.55%和8.97%.橄榄蚶软体部含有18种氨基酸,总氨基酸、必需氨基酸和呈味氨基酸分别占软体部干重的54.83%、19.80%和27.54%,总氨基酸占软体部蛋白质的86.13%,必需氨基酸和呈味氨基酸分别占氨基酸总量的36.11%和56.52%.橄榄蚶的限制性氨基酸为蛋氨酸+胱氨酸和色氨酸.橄榄蚶软体部含28种脂肪酸,不饱和脂肪酸(UFA)、单不饱和脂肪酸(MUFA)、多不饱和脂肪酸(PuFA)及"w-3系列多不饱和脂肪酸(w-3PUFA)分别占脂肪酸的41.31%、23.06%、18.25%和10.54%,DHA和EPA分别占脂肪酸的2.82%和4.59%.     

国内九种食用菌营养构成的分析

本文通过对全国第二届农业博览会参评的九种食用菌３９个样品的蛋白质、氨基酸等的测定,按照食用菌蛋白质的营养价值的评定标准,对其营养价值进行了评价。初步探讨了国内食用菌生产加工中存在的不足及改进的方向。     

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.     

Regulation of amino acid transport in growing cells of Streptomyces hydrogenans

(1) The active uptake of different amino acids by growing cells of Streptomyces hydrogenans was shown to be correlated with the physiological age of the cells. During the lag phase of growth the transport capacity increased and attained its highest level when the growth rate was maximum. During further growth the transport capacity declined progressively. The lowest transport activity was observed when the culture shifted into the stationary growth phase. (2) Such modulation of transport capacity was independent on the presence or absence of amino acids in the growth medium of the cells. (3) The size and the composition of the pool of free intracellular amino acids was also undergoing substantial variations during the growth cycle of the culture. In the lag phase, the levels of all amino acids decreased markedly and attained their lowest values at the end of this phase. During further growth the pool size was slowly replenished. (4) Removal of the pool resulted in a considerable gain of transport capacity. Therefore, it was concluded that active amino acid transport in growing Streptomyces hydrogenans is under feedback control by intracellular amino acids. (5) Quantitatively, the modulation of the pool size could not fully account for the variation of the transport capacity. Since a pool-independent stimulation of transport was found to be correlated with the increase of the growth rate of the cells, the possibility is discussed that the stimulation of transport is either due to increased levels of distinct RNA species, which might provide positive feedback signals for transport, or by increased rates of de novo synthesis of transport limiting proteins.List of Abbreviations AIB 2-aminoisobutyric acid - CM complete medium - MM mineral medium     

Neighboring-site effects of amino acid mutation

Although the context dependence of nucleotide mutation has been supported by accumulating theoretical and experimental evidence, whether this effect can be extended to amino acid mutation remains obscure. As the amino acid doublets (20 x 20) are much more diverse than their nucleotide counterparts (4 x 4), any attempt to address the neighboring-site effects of amino acid mutation was frustrated by deficient amino acid mutation data. Based on the recently revealed 599,745 mutation sites in 45,137 orthologous proteins, we provide solid evidence for the first time to support the existence of neighboring-site effects in amino acid mutation, which is significantly important to improving the prevalent protein-evolution models.     

Synthesis of symmetric and asymmetric diamides of citric acid and amino acids

Summary A convenient method for the synthesis of symmetric and asymmetric diamides of amino acids including DOPA and citric acid from 2-tert-butyl-1,3-di(N-hydroxysuccinimidyl)citrate and 1-tert-butyl-2,3-di(N-hydroxysuccinimidyl)citrate is described.Abbreviations AcOtBu tert-butyl acetate - i-Bu iso-butyl - tBu tert-butyl - Bzl benzyl - p-OH-Bzl p-hydroxybenzyl - m,p-(OH)₂-Bzl m,p-dihydroxybenzyl - DCCI dicyclohexylcarbodiimide - Et ethyl - Me methyl - Su succinimidyl - SuOH N-hydroxysuccinimide - Ph phenyl     

氨基酸肥效作用的研究

本研究证明氨基酸分子可以直接被作物吸收,并有促进作物增产的肥效作用,如与等氮量的无机氮肥相比(如NH_4Cl),混合氨基酸的肥效更高,我们用胱氨酸废液中的游离氨基酸为主要成分制成氨基酸肥料,盆栽和田间试验证明,该肥料具有明显增产作用,这就为毛发水解行业治理环境污染与开辟新的肥料来源结合起来,一举两得。     

A reduced amino acid alphabet for understanding and designing protein adaptation to mutation

Protein sequence world is considerably larger than structure world. In consequence, numerous non-related sequences may adopt similar 3D folds and different kinds of amino acids may thus be found in similar 3D structures. By grouping together the 20 amino acids into a smaller number of representative residues with similar features, sequence world simplification may be achieved. This clustering hence defines a reduced amino acid alphabet (reduced AAA). Numerous works have shown that protein 3D structures are composed of a limited number of building blocks, defining a structural alphabet. We previously identified such an alphabet composed of 16 representative structural motifs (5-residues length) called Protein Blocks (PBs). This alphabet permits to translate the structure (3D) in sequence of PBs (1D). Based on these two concepts, reduced AAA and PBs, we analyzed the distributions of the different kinds of amino acids and their equivalences in the structural context. Different reduced sets were considered. Recurrent amino acid associations were found in all the local structures while other were specific of some local structures (PBs) (e.g Cysteine, Histidine, Threonine and Serine for the alpha-helix Ncap). Some similar associations are found in other reduced AAAs, e.g Ile with Val, or hydrophobic aromatic residues Trp with Phe and Tyr. We put into evidence interesting alternative associations. This highlights the dependence on the information considered (sequence or structure). This approach, equivalent to a substitution matrix, could be useful for designing protein sequence with different features (for instance adaptation to environment) while preserving mainly the 3D fold.     

The amino acid sequence of two small ribosomal proteins from Bacillus stearothermophilus

The low-Mr proteins (tentatively called protein I and II) were purified from 2 M NaCl extracts of the Bacillus stearothermophilus ribosome. Their amino acid sequences have been determined from the peptides obtained by digestion with trypsin, chymotrypsin, and pepsin, and by cleavage with CNBr, using the micro-DABITC/PITC double-coupling method [FEBS Lett. (1978) 93, 205-214]. Protein I contains 56 residues and has an Mr of 6514. Protein II had 37 residues with an Mr of 4361. The amino acid sequence of protein I shows significant similarity to L32 from E. coli, whereas that of protein II is slightly, if at all, related to ribosomal protein L34 from E. coli.