Partial characterization of 21.5K myelin basic protein from sheep brain

The 21,500 molecular weight (21.5K) variant of myelin basic protein (MBP) was isolated from sheep brain and partially characterized. Digestion with cyanogen bromide and trypsin yielded peptides which showed that approximately 30 additional amino acids were inserted at the equivalent of the amino acid at position 57 in the bovine 18.5K MBP sequence. An unusually hydrophobic peptide Pro, Val, Leu, Trp, Lys was present in this region. Ornithine was present in hydrolyzates of 21.5K MBP, but it was not detected in any of the peptides.     

Side chain contributions to the stability of alpha-helical structure in peptides

Short peptides that contain significant alpha-helical structure in aqueous solution allow the investigation of the role of amino acid side chains in stabilizing or destabilizing alpha-helix structure. A host-guest system of soluble synthetic peptides was designed that consisted of chains with the block sequence TyrSerGlu4Lys4X3Glu4Lys4, denoted EXK, in which X represents any "guest" amino acid residue. Circular dichroism spectroscopy indicates that the extent of helicity of these peptides follows the order Ala greater than Leu greater than Met greater than Gln greater than Ile greater than Val greater than Ser greater than Thr greater than Asn greater than Gly. This order differs from both host-guest copolymer values (Met greater than Ile greater than Leu greater than Ala greater than Gln greater than Val greater than Thr greater than Asn greater than Ser greater than Gly) and the tendencies of these amino acids to occur in helices in globular proteins (Ala greater than Met greater than Leu greater than Gln greater than Ile greater than Val greater than Asn, Thr greater than Ser greater than Gly), but matches the order found in a series of synthetic coiled-coil alpha helices, except for Ser. Proton nuclear magnetic resonance analysis of several EXK peptides indicates that these peptides are partially helical, with the helical residues favoring the amino terminus.     

Investigating structural impact of a valine to isoleucine substitution on anti-Müllerian hormone in silico and genetic association of the variant and AMH expression with egg production in chickens

Anti-Müllerian hormone(AMH) acts in maintaining orderly cyclic recruitment of early follicles, suggesting that it is a promising candidate for influencing animal reproductive efficiency. This study aimed to elucidate the effect of a missense mutation of Val~(566) Ile on the structure of AMH protein and the genetic association of Val~(566) Ile and AMH expression with egg production in chickens. Structural perturbations of Val~(566) Ile were predicted by homology modeling. The association of the variant with the number of eggs was tested using a quantitative trait transmission disequilibrium test model. AMH expression in granulosa cells in Lueyang black-boned chickens was compared with that in Nick chickens. The Val~(566) of AMH is a nonconservative amino acid among mammals and birds, but its hydrophobicity is completely conservative. The substitution of Val~(566) for Ile~(566) potentially disrupted hydrogen bonds and solvent accessibility of 22 residues and created a short α-helix in the C terminus of AMH. Despite having striking structure-disrupting potential, the variant was not statistically associated with the number of eggs(P0.05) in the Lueyang black-boned chickens. We did not detect differential expression of AMH between Lueyang black-boned chickens and Nick chickens(P0.05). These results confirmed the structural impact of Val~(566) Ile, but suggested that Val~(566) Ile and AMH expression might not be the major genetic determinants for egg production in Lueyang black-boned chickens.     

Trans-suppression of misfolding in an amyloid disease

The transthyretin (TTR) amyloid diseases, representative of numerous misfolding disorders, are of considerable interest because there are mutations that cause or suppress disease. The Val30 --> Met30 (V30M) TTR mutation is the most prevalent cause of familial amyloid polyneuropathy in heterozygotes, whereas a Thr119 --> Met119 (T119M) mutation on the second TTR allele protects V30M carriers from disease. Here, we show that the incorporation of one or more T119M TTR subunits into a predominantly V30M tetramer strongly stabilized the mixed tetramer against dissociation. Dissociation is required for amyloid formation, so these findings provide a molecular explanation for intragenic trans-suppression of amyloidosis. The data also suggest a potential therapeutic strategy, provide insight into tissue-specific deposition and amyloid composition, and support the validity of the amyloid hypothesis in human disease.     

Studies on Models,Patterns and Require-ments of Digestible Amino Acids for Layers by Nitrogen Metabolism

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小麦抗感白粉病品种游离氨基酸含量的比较分析

测定7个小麦抗感白粉病品种苗期、11个品种成株期叶片的游离氨基酸含量。结果表明,苗期抗病品种叶片各游离氨基酸中,缬氨酸、苯丙氨酸、组氨酸和精氨酸平均含量明显高于感病品种,与病情指数呈明显负相关,而其它12种游离氨基酸平均含量抗感品种间无明显差异。成株期倒2叶游离氨基酸中,缬氨酸、甲硫氨酸、异亮氨酸、亮氨酸、酪氨酸、苯丙氨酸、赖氨酸、组氨酸、色氨酸、精氨酸及总游离氨基酸含量,均显著低于感病品种,且与病情指数呈明显正相关。各游离氨基酸平均含量苗期和成株期抗感品种间差异均不一致。     

金针菇深层发酵的研究──Ⅰ．金针菇发酵滤液游离氨基酸的分析

金针菇深层发酵滤液中游离的必需氨基酸占游离氨基酸总量的８０％左右．主要积累的氨基酸为赖氨酸、苯丙氨酸、缬氨酸、蛋氨酸、亮氨酸和精氨酸等．氨基酸的积累情况可归纳为３个类型：第１型为苯丙氨酸＞缬氨酸＞赖氨酸＞蛋氨酸．第２型为赖氨酸＞蛋氨酸＞苯丙氨酸＞缬氨酸．第３型为亮氨酸＞缬氨酸＞赖氨酸＞蛋氨酸．３个类型的共同特点是赖氨酸始终是大量积累的主要氨基酸之一以及必需氨基酸所占的百分比都很高，差异仅在个别氨基酸积累量的多少上．对这种差异的原因进行初步探讨发现：（ＮＨ４）２ＳＯ４浓度和黄豆粉作氮源影响游离氨基酸的总产量和必需氨基酸所占的百分比，而不影响高含量氨基酸的种类．ＰＯ４３－的浓度不同对其差异没有影响．     

Evaluation of Apparent Metabolic Energy,Nitrogen Corrected Metabolic Energy,Biological Value of Protein and Ileal Digestibility of Amino Acid of Yeast Hydrolysate for Broilers

【Objective】 The purpose of this study was to evaluate the apparent metabolic energy, nitrogen-corrected apparent metabolic energy, ileal apparent amino acid digestibility, standard ileal amino acid digestibility and total intestinal apparent amino acid digestibility of yeast hydrolysate in broilers, so as to provide the reference for the wide application of yeast hydrolysate in broiler diets. 【Method】 A total of 160 Cobb white-feathered broilers at 18 days old with no difference in body weight were randomly divided into the control group and experimental group. There were 8 replicates in each group, and 10 chickens with half male and half female were in each replicate. The control group was fed a nitrogen-free diet consisting of corn starch, glucose, fiber and soybean oil, and the experimental group was fed a semi-homozygous diet using yeast hydrolysate as the sole crude protein source. Furthermore, the control group and the experimental group were fed with 0.5% titanium dioxide, respectively, as an exogenous indicator. During the whole experiment, free feeding was available for broilers, feces were collected on 22-24 days using total fecal collection method, and the feed intake of broilers was counted. Further, the apparent metabolic energy of yeast hydrolysate and nitrogen-corrected apparent metabolic energy were calculated by measuring the total energy and nitrogen content in both diets and feces of broilers. After26 days of experiment, the latter half of ileum was dissected under anesthesia, the chime was taken out, and the contents of amino acids and titanium dioxide in both diet and ileal chyme were measured to calculate the apparent amino acid digestibility, standard ileal amino acid digestibility and total intestinal apparent amino acid digestibility of yeast hydrolysate. 【Result】 (1) The total energy value of yeast hydrolysate was 18.19 MJ·kg ^-1, the apparent metabolic energy value was 11.22 MJ·kg ^-1, and the nitrogen-corrected apparent metabolic energy was 10.17 MJ·kg ^-1. Effective energy was equivalent to that of common soybean meal. (2) Crude protein content of yeast hydrolysate was 41.7%, and total amino acid was 36.97%. The ratio of essential amino acid to dispensable amino acid was 44:56, which was close to that of common soybean meal. The limiting amino acids of yeast hydrolysate were Met, Met+Cys, Arg, Leu, Ile, Phe+Tyr, Val, His, lys, Thr and Trp, which were different from soybean meal. (3) The ileal apparent amino acid digestibility, standard ileal amino acid digestibility and total intestinal apparent amino acid digestibility of yeast hydrolysate were all higher than 70%. The available limiting amino acids were Met, Met+Cys, Arg, Leu, Ile, Thr, Phe+Tyr, His, Lys, Val, and Trp. Methionine and arginine were the first and the second limiting amino acids, and leucine and isoleucine were the third and the fourth limiting amino acids, respectively. Threonine was poorly available, and was regarded as the fifth restrictive available amino acid. In addition, the limiting amino acids of yeast hydrolysate were quite different to soybean meal. 【Conclusion】 Yeast hydrolysate was a kind of protein feed material. Its protein content and effective energy value were similar to soybean meal, but its amino acid composition and availability were quite different to soybean meal. Therefore, in the application of yeast hydrolysate in broiler diet, it was necessary to consider the need of supplementing different amino acids or mixing different protein feeds to balance amino acids.     

肉鸡酵母水解物代谢能及氨基酸可利用率评定

【目的】 评定肉鸡对酵母水解物的表观代谢能、氮校正表观代谢能、回肠表观氨基酸消化率、标准回肠氨基酸消化率、全肠道表观氨基酸消化率,拟为酵母水解物在肉鸡饲粮中的广泛应用提供基础参数。【方法】 选择18 d、体重无差异的科宝白羽肉仔鸡160只,随机分成对照组和试验组,每组8个重复,每个重复10只试验鸡,公母各半。对照组饲喂以玉米淀粉、葡萄糖、纤维、大豆油配制的无氮日粮,试验组饲喂以酵母水解物为唯一粗蛋白质来源的半纯合日粮,对照组和试验组均添加0.5%的二氧化钛作为外源指示剂。试验期间自由采食,全收粪法收集试验鸡22—24 d粪便,并统计该期间肉鸡采食量,通过检测日粮以及粪便中总能、含氮量来计算酵母水解物表观代谢能值和氮校正表观代谢能值。粪便收集完后自由采食,26日龄麻醉剖解收集回肠后半段食靡,分别检测日粮、回肠食糜中氨基酸及二氧化钛含量,计算酵母水解物回肠表观氨基酸消化率、标准回肠氨基酸消化率、全肠道表观氨基酸消化率。【结果】 （1）酵母水解物总能值为18.19 MJ·kg ^-1,表观代谢能值为11.22 MJ·kg ^-1,氮校正表观代谢能为10.17 MJ·kg ^-1,其有效能值与普通豆粕相当。（2）酵母水解物粗蛋白质含量为41.7%,总氨基为36.97%,必需氨基酸与非必需氨基酸之比为44﹕56,与普通豆粕接近;酵母水解物肉鸡限制性氨基酸依次为Met、Met+Cys、Arg、Leu、Ile、Phe+Tyr、Val、His、Lys、Thr、Trp,与豆粕差异较大。（3）酵母水解物回肠表观氨基酸消化率、标准回肠氨基酸消化率、全肠道表观氨基酸消化率均大于70%,肉鸡可利用限制性氨基酸依次为Met、Met+Cys、Arg、Leu、Ile、Thr、Phe+Tyr、His、lys、Val、Trp,蛋氨酸、精氨酸为第一、第二限制性可利用氨基酸,亮氨酸、异亮氨酸为第三、第四限制性可利用氨基酸,苏氨酸可利用较差,为第五限制性可利用氨酸,酵母水解物限制性氨基酸与豆粕差异较大。【结论】 酵母水解物是一种蛋白饲料原料,其蛋白质含量、有效能值与豆粕相当,但其氨基酸组成及氨基酸可利用率与豆粕存在较大差异。因此,酵母水解物在肉鸡日粮中应用,需要考虑补充不同氨基酸或者搭配不同蛋白质饲料来平衡氨基酸的需要。     

小麦品种对麦长管蚜抗性机制的研究

对16个小麦品种抗蚜性鉴定结果表明,品种旗叶中Gly.、Cys含量越高,有翅蚜的着落量越大,而Leu.、Ala.、Pro.含量越高,着落量越小;Gly.含量越高,r_m值越小,而Pro.、Met.、His.含量越高,r_m值越大Lys.、Val.、Cys.、Tyr.、Met.含量与蚜群发育历期有关,前2种含量越高,D值越大,后3种含量越高,D值越小His.、Tyr.、Lys.、Ala.含量与蚜群平均产仔量有关Cys.、Glu.、Gly.、Val.含量与平均产仔速率有关;品种耐害性强弱除与品种小穗密度有关外,也与品种旗叶中氨基酸含量密不可分,His.、Glu.、Lys.含量越高耐害性越差.而Pro.、Met.、Val.等含量越高,品种的耐害性越强.     

绵羊UCP1基因碱基突变与其蛋白结构和功能

【目的】检测两个绵羊群体中解偶联蛋白1（uncoupling protein 1,UCP1）基因的单核苷酸多态性 （single nucleotide polymorphism,SNP）,预测和分析碱基改变对蛋白结构和功能的影响。【方法】利用PCR-SSCP结合测序的方法检测UCP1基因编码区的SNPs,用生物信息学方法分析UCP1蛋白的理化性质和结构。【结果】UCP1基因编码区存在4个SNPs,其中c.214G＞A（Val72Met）和c.273C＞T位于外显子2,c.624C＞T和c.757G＞A（Ala253Thr）位于外显子5。进一步分析导致氨基酸改变的c.214G＞A和c.757 G＞A突变发现,此两个突变只对UCP1蛋白的理化性质和转录因子结合位点有细微改变,未引起UCP1蛋白空间构象的变化,对蛋白表达的影响不大。【结论】基于对人类中两个与肥胖相关的外显子突变型蛋白结构的比较说明,UCP1蛋白结构的改变可能影响其功能。     

贵州黔东南3种野生棘蛙肌肉的氨基酸组成与含量

为了解贵州黔东南棘蛙的肌肉营养价值,采用常规氨基酸分析方法测定黔东南棘胸蛙、棘侧蛙和棘腹蛙3种野生棘蛙肌肉的氨基酸组成与含量,并以鸡蛋蛋白质为标准蛋白,以WHO/FAO氨基酸参考模式为标准对其进行氨基酸营养评价。结果表明:黔东南3种野生棘蛙肌肉的氨基酸组成一致,其中含有苏氨酸、缬氨酸、蛋氨酸、异亮氨酸、亮氨酸、苯丙氨酸和赖氨酸7种人体必需氨基酸,非必需氨基酸5种,天冬氨酸、谷氨酸、甘氨酸和丙氨酸4种鲜味氨基酸。棘胸蛙、棘腹蛙和棘侧蛙肌肉中氨基酸总量分别为84.19%、87.43%和86.12%。必需氨基酸含量占总氨基酸含量的比值分别为39.79%、40.07%和39.06%,在蛙科动物中均属于较高水平。3种棘蛙肌肉中,均以谷氨酸的含量最高,天冬氨酸的含量次之,蛋氨酸含量最低。氨基酸评分(AAS)和化学评分(CS)表明,棘蛙肌肉中第一限制性氨基酸为蛋氨酸,第二限制性氨基酸为缬氨酸。必需氨基酸指数(EAAI)显示,棘胸蛙为86.72、棘腹蛙为89.79、棘侧蛙为86.22。综合各项指标分析,贵州黔东南3种野生棘蛙具有较高的经济价值。     

肉仔鸡胴体和羽毛蛋白的氨基酸组成模式

为了确立肉仔鸡胴体和羽毛蛋白的氨基酸组成模式,分别选用0,14,28,42日龄的Arbor Acres公母肉仔鸡各6只,颈骨错位致死后分离羽毛和胴体,将胴体和羽毛分别加工处理,测定其粗蛋白质及各种氨基酸含量,并将各种氨基酸含量表示为占粗蛋白质百分比的形式。结果表明,性别对肉仔鸡胴体和羽毛蛋白的氨基酸组成没有影响(P>0.05);除胴体蛋白中天冬氨酸、甘氨酸、丙氨酸、赖氨酸、色氨酸和羽毛蛋白中天冬氨酸、丝氨酸、谷氨酸、胱氨酸、缬氨酸、异亮氨酸、亮氨酸外,日龄对胴体和羽毛蛋白其他氨基酸组成模式均有显著影响(P<0.05),胴体蛋白中苏氨酸、丝氨酸、谷氨酸、胱氨酸、蛋氨酸、亮氨酸、酪氨酸、苯丙氨酸、组氨酸、精氨酸、脯氨酸和羽毛蛋白中苏氨酸、甘氨酸、丙氨酸、酪氨酸、苯丙氨酸、精氨酸和脯氨酸组成模式在14,28和42日龄间均无显著差异(P>0.05)。而胴体蛋白中缬氨酸、异亮氨酸和羽毛蛋白中蛋氨酸、赖氨酸、组氨酸和色氨酸组成模式在不同日龄间差异均达显著水平(P<0.05)。综合考虑认为,以14,28和42日龄的平均值作为确立肉仔鸡胴体和羽毛蛋白氨基酸模式的依据。     

庄河产薏苡仁中氨基酸含量的测定

按照国标GB/T 5009.124-2003方法处理样品,对庄河产薏苡仁中氨基酸的含量进行了测定。结果表明,庄河产薏苡仁中含有16种氨基酸,Asp、Thr、Ser、Glu、Gly、Ala、Val、Met、Ile、Leu、Tyr、Phe、Lys、His、Arg、Pro的含量分别为1 350.0、252.0、349.0、1 480.0、214.0、699.0、297.0、84.3、181.0、544.0、169.0、215.0、208.0、170.0、456.0、846.0μg/kg。     

3种羊奶干酪成熟期间蛋白质降解的研究

对 3种羊奶干酪成熟期间蛋白质降解的研究表明 ,鲜干酪成熟期间 p H较高 ,化学成分变化不大 ,整个成熟期间蛋白质降解较少。半硬质干酪和硬质干酪成熟初期蛋白质降解较快 ,后期缓慢 ,主要形成氨基酸和短肽。总游离氨基酸随成熟期延长逐渐增加 ,主要是 Ser,Glu,Pro,Ala,Val,Met,L eu和 L ys。     

红霉素药渣作家禽蛋白质饲料的营养价值评价

用蛋白质自动定氮仪和Beckman-121MB型氨基酸分析仪测定红霉素药渣,粗蛋白质为18.38 %,10种必需氨基酸总含量为3.839 %,其中赖氨酸0.265 %、蛋+胱氨酸0.704 %、色氨酸0.347 %、苏氨酸0.213 %、亮氨酸0.690 %、缬氨酸0.343 %、异亮氨酸0.375 %、苯丙+酪氨酸0.400 %、组氨酸0.282 %、精氨酸0.220 %。真可利用蛋氨酸(0.53 %)与大豆饼(0.54 %)接近。以家禽理想蛋白质为模型计算必需氨基酸平衡指数(IEAA)是0.662～1.323,结合失衡度等指数的计算结果,证实红霉素药渣为家禽饲料的良好蛋白源。     

Protein synthesis and neurotrophin-dependent structural plasticity of single dendritic spines

Long-term potentiation (LTP) at glutamatergic synapses is considered to underlie learning and memory and is associated with the enlargement of dendritic spines. Because the consolidation of memory and LTP require protein synthesis, it is important to clarify how protein synthesis affects spine enlargement. In rat brain slices, the repetitive pairing of postsynaptic spikes and two-photon uncaging of glutamate at single spines (a spike-timing protocol) produced both immediate and gradual phases of spine enlargement in CA1 pyramidal neurons. The gradual enlargement was strongly dependent on protein synthesis and brain-derived neurotrophic factor (BDNF) action, often associated with spine twitching, and was induced specifically at the spines that were immediately enlarged by the synaptic stimulation. Thus, this spike-timing protocol is an efficient trigger for BDNF secretion and induces protein synthesis-dependent long-term enlargement at the level of single spines.     

灰色关联分析硒镧复合作用下巴西蘑菇氨基酸含量与铅含量的关系

用灰色系统理论分析硒镧复合作用下巴西蘑菇子实体中17种氨基酸含量与重金属铅含量的关系。结果表明：在硒镧复合作用下,巴西蘑菇子实体氨基酸含量与铅含量的关联度顺序为：异亮氨酸〉赖氨酸〉缬草氨酸〉脯氨酸〉亮氨酸〉丝氨酸〉苯丙氨酸〉天门冬氨酸〉甘氨酸〉精氨酸〉丝氨酸〉组氨酸〉胱氨酸〉酪氨酸〉苏氨酸〉丙氨酸〉甲硫氨酸。其中,异亮氨酸含量与重金属铅含量关联度最大,为0．8148。关联度越大,相似程度就越高,说明硒镧复合作用下巴西蘑菇子实体中异亮氨酸含量与重金属铅含量的关系最为密切;其次是赖氨酸和缬氨酸。关联度最小的是甲硫氨酸。各处理的关联度及排序为：B4〉B0〉B3〉B1〉B2。其中,B4处理关联度最大,B2处理关联度最小。说明硒镧浓度对巴西蘑菇子实体铅含量与各氨基酸含量有一定效应。     

不同栽培法对晚稻氨基酸含量影响及其机理的研究

为给高蛋白高产栽培综合技术体系的推广应用提供理论依据,以高蛋白的培两优288和低蛋白的培两优210为材料,采用田间裂区试验设计,研究了高蛋白高产栽培综合技术体系、三壮三高栽培法、常规栽培法3种不同栽培法对高蛋白和低蛋白两个杂交晚稻组合功能叶及籽粒中谷草转氨酶(GOT)与天冬氨酸激酶(AK)活性的影响。结果表明:与三壮三高栽培法、常规栽培法相比,高蛋白高产栽培综合技术体系能够有效提高晚稻蜡熟期和黄熟期功能叶及籽粒中GOT和AK的活性,且在高蛋白组合和低蛋白组合上都有较好的应用效果;功能叶中GOT和AK的活性在蜡熟期分别提高了11.41%￣27.72%和7.96%￣47.45%,功能叶中AK的活性在黄熟期提高了21.61%￣163.76%;籽粒中GOT和AK的活性在黄熟期分别提高了127.33%￣175.36%和16.36%￣89.13%。功能叶和籽粒中GOT和AK活性的提高有效促进了晚稻蛋白质和氨基酸的合成,使得(添加)糙米蛋白质含量的增幅为1.61gkg￣23.26g/kg;氨基酸含量的增幅为2.24%￣44.09%。其中人体7种必需氨基酸的含量增加9.20%￣58.05%;猪11种必需氨基酸的含量增加4.47%￣66.36%。