酶解Shi鱼可溶性肽分子组成结构及营养评价

本文叙述了用胃蛋白酶、胰蛋白酶水解的Shi鱼可溶性肽类水解物,经凝胶高效液相色谱和氨基酸分析仪分析测定其肽类分子组成结构和氨基酸组成成分。测得水解产物中肽类相对分子质量在7400以下,其中相对分子质量6600－7400、由52－58个氨基酸组成的较长肽链占1．74％;相对分子质量2500－5300、由20－41个氨基酸组成的中长肽链占29．75％;相对分子质量在1000以下的由2－10个氨基酸组成的寡肽占50％。水解物的总氮与氨基酸态氮比为25．9：1,约有96％的氨基酸以肽类形式存在,4%为游离氨基酸。测得可溶性肽的总氨基酸含量为73．98％,必需氨基酸为32．39％,占总氨基酸的43．78％,与FAO／WHO相比,苯丙氨酸为第一限制性氨基酸,氨基酸分值为61。根据分析结果,深入探讨了Shi鱼可溶性肽氨基酸组成的平衡性及其有关寡肽在动物机体的生理功能作用。     

脑蛋白水解物制剂的质量标准及不良反应

目的:探讨脑蛋白水解物制剂的质量标准的完善,减少和避免有关不良反应,以促进临床合理用药。方法:根据文献,对不同厂家生产的脑蛋白水解物制剂的药品说明书、质量标准及其有关不良反应进行统计和分析。结果与结论:目前市售脑蛋白水解物制剂分为片剂和注射剂,其片剂说明书中均标明氨基氮及总氮量,而注射剂中大多未标明氨基酸、总氮和肽的含量。其质量标准通过鉴别和检查进行定性检查,各项检查应符合要求;片剂中氮含量测定参考2010年版《中国药典》的相关方法,注射剂中氨基酸等的含量测定参考相关文献,氨基酸总量应为28.08～42.14mg·mL-1,总氮量5.49～6.71mg·mL-1,含肽量15%～30%。其不良反应以过敏反应为常见。应完善脑蛋白水解物制剂的质量标准,规范药品说明书,以便于个体化给药,避免因药品质量或用药剂量不准确而引发不良反应。     

依替巴肽一级结构的确证

目的:对合成的依替巴肽一级结构进行确证。方法:采用串联质谱序列分析法测定了氨基酸序列,采用 ESI-MS/MS 对依替巴肽的相对分子质量和肽链环化结构进行了确证,采用~1 HNMR 进一步确定了依替巴肽的结构。结果:串联质谱序列分析法,证实合成肽氨基酸序列和非天然氨基酸结构正确;ESI-MS/MS 测得样品准确的相对分子质量为831.48,与依替巴肽的参照品及理论值(831.96)完全一致;质谱分析确证合成依替巴肽分子内形成了一个正确的二硫键;~1 HNMR 进一步确定了依替巴肽分子的一级结构。结论:本文对依替巴肽的氨基酸序列以及一级结构全序列进行了确证。     

脑蛋白水解物片剂肽含量测定方法的改进

目的：优化脑蛋白水解物片中肽含量测定方法。方法：采用分子排阻色谱法鉴别脑蛋白水解物片中小分子肽类、高效液相色谱法测定脑蛋白水解物片中肽含量。结果：分子排阻色谱法鉴别小分子肽特异性强;高效液相色谱法测定的各种氨基酸在一定的浓度范围内与峰面积呈良好的线性关系（r＞0.999）,平均回收率为98.0%～102.4%。结论：该方法快速、简便、专属性强、重复性好,结果准确可靠,适用于脑蛋白水解物片的质量控制。     

奥曲肽一级结构的确证

目的：对奥曲肽(人工合成8肽)的一级结构进行确证。方法：采用：HPLC法测定了奥曲肽的氨基酸组成，采用：Edman降解法测定了除苏氨醇外的7个氨基酸的序列，采用ESI—MS／MS对奥曲肽的分子量以及C—末端的苏氨醇残基进行了确证。结果：采用HPLC法测得除色氨酸以外，样品的氨基酸组成与理论值基本一致。采用Edman降解法测得除苏氨醇外其余7个氨基酸序列与理论结构一致。采用ESI—MS／MS测得样品的相对分子质量为1018．7，与理论值1019．3基本符合。对二级质谱碎片的解析确证样品C—末端确为苏氨醇残基。结论：本文对奥曲肽的C—末端苏氨醇残基以及一级结构全序列进行了确证。     

基于寡肽转运体的缬沙坦拟肽前药设计与合成

目的为了改善缬沙坦的口服生物利用度,基于寡肽转运体(oligopeptide transporter,Pep T)的转运特点,设计并合成基于寡肽转运体的缬沙坦拟肽系列前药。方法基于寡肽转运体底物模型和缬沙坦分子结构,设计12个缬沙坦拟肽前药;以Trt-缬沙坦和带保护基的氨基酸原料,经缩合、脱保护得到2个缬沙坦氨基酸酯;以带保护基的不同氨基酸为原料,缩合得系列二肽化合物,然后分别与Trt-缬沙坦经缩合、脱保护得到10个缬沙坦二肽酯。结果合成了12个基于寡肽转运体的缬沙坦拟肽前药,目标化合物与关键中间体的化学结构经1H-NMR、MS确证。结论基于Pep T的底物特征,设计并合成了12个缬沙坦拟肽前药,为该类前药的深入研究奠定基础。     

一条新的可诱导PC12细胞转化为交感神经原表型的小分子肽链

目的根据神经生长因子 (NGF)的氨基酸序列及其晶体构象资料 ,对 β NGF进行限制性酶解 ,从而获得关键的功能区域片段。方法选择溴化氰在 9位Met处 ,Trypsin在Arg或Lys处裂解 β NGF ,用SephadexG 5 0色谱、DE5 2离子交换色谱和反相高效液相色谱进行分离纯化。所得片段用PC12细胞测定活性 ,对活性片段进行氨基酸组成及序列分析。结果从 β NGF裂解片段中获得一可诱导PC12细胞分化的活性片段 ,氨基酸组成及序列分析表明 ,此片段由 16肽GEFSVCDSVSVWVGDK与 14肽HWNSYCTTTHTFVK通过一对二硫键连接而成 ,与 β NGF肽链的10～ 2 5和 75～ 88氨基酸残基序列相对应。生物活性分析表明其最佳作用浓度为 0 .0 0 1～ 0 .1ng/ml。结论此实验获得了 β NGF关键的功能区域片段 ,虽然其空间结构和功能的关系尚需研究探讨 ,但它的成功分离和鉴定为合成或表达高活性小分子神经营养物质奠定了重要的基础     

广西菲牛蛭水蛭素基因cDNA的克隆与序列分析

目的克隆广西菲牛蛭水蛭素基因的cDNA,并对该基因以及氨基酸进行序列分析。方法根据已发表的马尼拉菲牛蛭水蛭素基因cDNA设计一对引物,从广西菲牛蛭的头部提取总RNA后,采用RT-PCR扩增cDNA,将产物克隆至载体PMD-19T,PCR鉴定后进行测序。结果广西菲牛蛭水蛭素基因cDNA序列长度为251 bp,编码框由83个氨基酸组成,其中包括由20个氨基酸的信号肽,以及63个氨基酸组成的成熟肽。广西菲牛蛭水蛭素基因的氨基酸序列和已报道的广东菲牛蛭、马尼拉菲牛蛭水蛭素基因HM1、HM2基因的氨基酸序列相比较,同源性分别为94%,91.8%,84.7%。结论广西菲牛蛭水蛭素基因cDNA序列长度为251 bp,由83个氨基酸组成。     

肝细胞生长素的研究概况

肝细胞生长素的研究概况崔速南汪明明闫玉萍（济南市传染病医院济南２５００２１）肝细胞生长素（Ｈｅｐａｔｏｃｙｔｉｃｇｒｏｗｔｈｆａｃｔｏｒ，ＨＧＦ）是重要的促有丝分裂原，能促进肝细胞再生。其多肽结构由７２８个氨基酸组成，相对分子质量为８２Ｋｄ，整个肽链...     

牛、猪脑的酶水解物在神经科的临床应用

<正> 脑去脂后的酶水解物即脑的酶水解物(brain hydrolysate),可用于治疗一些脑功能性疾病,在欧洲及远东国家已逐渐开展。其中主要成分是氨基酸及肽类。 1 脑内氨基酸的生化、生理 Yasuzo等对哺乳类、鸟类、爬虫类,两栖类及软体类动物的脑中氨基酸曾比较其定性、定量测定,了解其共有的氨基酸是天冬氨酸、谷     

口服水解蛋白的成分分析

目的 分析口服水解蛋白的组成成分及分子量分布范围.方法 通过PITC柱前衍生法对口服水解蛋白的游离氨基酸含量进行测定,并通过质谱扫描及凝胶色谱方法测定分子量分布范围,分析口服水解蛋白的组成成分.结果 口服水解蛋白分子量范围在100～300 Da左右,口服水解蛋白含有18种氨基酸,其中8种为人体必需氨基酸,人体必需氨基酸含量占游离氨基酸总和的56.1％.口服水解蛋白的短肽含量与游离氨基酸含量比值为1.08.结论 本实验分析了口服水解蛋白的组成成分,口服水解蛋白是无脂,主要以短肽、混合氨基酸为主,含有少量糖类及矿物质的高蛋白营养补充剂.     

ISOLATION AND CHARACTERIZATION OF THE CYANOGEN BROMIDE FRAGMENTS OF LOBSTER ARGININE KINASE (HOMARUS VULGARIS)

Arginine kinase was aminoethylated in order to block the five free thiol groups on the native enzyme, and then submitted to BrCN cleavage. The BrCN resulting peptides were soluble in propionic acid (10%) and subsequently submitted to gel-filtration. The large polypeptide subfractions were citraconylated and resubmitted to different gelchromatographies, whereas the short peptide subfractions were submitted to preparative paper electrochromatographies. Eight peptides of 2, 11, 17, 25, 61, 82, 86 and 132 amino acid residues were isolated, one of which is the overlapping of two peptides. The amino acid composition and the end group of all the isolated peptides were established. The short peptides (2, 11 and 17 residues) were sequenced. All peptides possess homoserine at C-terminal position because one methionyl residue is situated at the C-terminal position in the native protein. The polypeptide with 132 residues possessed N-acetylated residue at N-terminal position; therefore this polypeptide is located at the N-terminal position in the protein. The sum and account of each amino acid of the seven isolated peptides were compared to those of the intact protein: the sum of the seven peptides is 331 amino acid residues, whereas the whole protein contains 342 residues. The molecular weight of arginine kinase is revised and calculated on the basis of the present results (37, 687).     

方格星虫多肽的结构分析及体外抗氧化活性

目的 以方格星虫为原料,酶解制备水溶性多肽并考察其抗氧化活性,探究其结构-活性关系。方法 利用5种蛋白酶酶解新鲜方格星虫,并结合超滤方法得到高分子量(>50kDa)、中分子量(5～50 kDa)和低分子量(＜5kDa)的酶解肽段;利用氨基酸自动分析仪测定方格星虫酶解肽的氨基酸组成。综合考察多肽对1,1-二苯基-2-苦基肼(DPPH.)自由基、羟基自由(.OH)、超氧阴离子自由基( O-2.)的清除能力以及还原力效果,评价方格星虫多肽抗氧化活性;利用高效液相色谱-串联质谱方法鉴定小分子肽的氨基酸组成和序列结构。结果 胰蛋白酶水解方格星虫4h得到的酶解液蛋白含量最高,并在酶解液中检测确定了17种氨基酸,其中精氨酸含量最高13.65%。高中低三组肽段中,低分子量肽段的抗氧化活性优于其他：对DPPH 自由基和羟自由基清除能力大小顺序为低分子量>高分子量>中分子量、对超氧阴离子清除能力大小顺序为低分子量>高分子量≈ 中分子量、还原能力强弱顺序为高分子量>低分子量 > 中分子量。经高效液相色谱-串联质谱联鉴定了GFAGDDAPR、GLGGLSPEK 、LDLAGR和VTKEIPR 4个肽段。结论 低分子量的方格星虫酶解多肽具有较好的抗氧化活性,有潜力用作生物医药或化妆品工业的原料。     

Quantitative structure-activity relationships of the bitter thresholds of amino acids, peptides, and their derivatives

Bitter thresholds of a total of 93 amino acids, peptides, and their derivatives were analyzed quantitatively by use of hydrophobicity parameters reported for amino acid side chains and those for the whole molecules estimated from partition coefficients obtained experimentally. We also explored the steric parameters that best explained the variation in the intensity of bitterness attributable to the molecular shape. The results showed that the total length along the zigzag peptide backbone chain of the molecule is an important factor. The bitterness of nonzwitterionic N-acyl and ester derivatives and that of neutral N-acyl ester derivatives were expressed by a single, common equation together with those of zwitterionic amino acids and peptides. Thus the interaction via the charge with the receptor site was probably not an indispensible factor for triggering of the bitter sensation. This study, together with earlier ones, may serve as a prototype of approaches toward unraveling structure-activity relationships of complex molecules like amino acids, peptides, and their derivatives that are of medicinal or agricultural importance.     

天然麝香抗炎有效成分的研究

天然麝香是雄性麝(Moschus mosohiferus L)的腺分泌物干燥粉末,有强烈香气,是珍贵药材。医学研究证明,麝香对中枢神经与心脏具有一定作用,并能降压,加强儿茶酚胺对β-受体的兴奋作用还具有雄激素样作用及显著的抗炎作用。 天然麝香的化学成分,过去重点研究了其亲脂性部分,但对水溶性成分缺乏研究。我们发现麝香水溶性部分有明显的抗炎活性,并从中分出一个主要抗炎有效成分-麝香抗炎     

Azapeptides as pharmacological agents

Azapeptides, formed by replacing the C(alpha) of amino acid residues by nitrogen, are promising peptidomimetic compounds. Azaamino acids impart a unique conformational property to peptide structures because of the loss of chirality and reduction of flexibility of the parent linear peptide. The peculiar conformational properties make azaamino acids an attractive tool for drug design involving specific secondary structures in peptides and proteins. Additionally, since azapeptides are less susceptible to enzymatic breakdown by proteases, they may possibly lead to orally active drugs with longer duration of action. One of the advantages of azapeptides is their unproblematic synthesis allowing retention of the amino acid side chain. Azapeptides have been developed by several groups for the design of hormone analogues, protease inhibitors and active site titrants.     

羊胎提取液的实验研究

目的对羊胎提取液的理化性质及生物学活性进行初步研究。方法理化性质检测采用光谱法、液相色谱法、氨基酸分析法等 ,活性测定采用活性E花环试验法和淋巴细胞转化实验法。结果羊胎提取液是多肽和核酸的混合成分 ,pH 6 .8～ 7.5 ,在 2 5 1nm波长处有一特征吸收 ,含 17种氨基酸。多肽、核酸、总氮含量和分子量依据不同工艺而定 ,蛋白质反应阴性 ,具有明显的细胞免疫调节功能。结论羊胎提取液可作为一种新型的免疫调节剂     

液质联用分析重组人白细胞介素-11的肽图

目的用液质联用技术分析鉴定重组人白细胞介素-11(rhIL-11)的肽图。方法用胰蛋白酶酶解rhIL-11，采用HPLC测定肽图，用电喷雾-四极杆-飞行时间质谱(ESI-Q-TOF/MS)技术分析肽段的精确相对分子质量，通过串联质谱(MS/MS)测定肽段的氨基酸序列。结果根据肽段的色谱保留时间、相对分子质量及对其碰撞诱导解离质谱的解析结果，归属出肽图中各肽段所在的色谱峰，已检出肽段的总覆盖率为97%。结论液质联用研究肽图是验证和分析蛋白质结构的高效准确的方法。     

Head-to-tail sequences and other patterns of peptide aggregation in the solid state

Encouraged by the results of our earlier study on the occurrence and the geometrical features of head-to-tail sequences involving amino acids, which have been suggested to be of probable relevance to prebiotic polymerisation, the available crystal structures of unprotected peptides have been analysed with a view to investigating head-to-tail sequences and other patterns of peptide aggregation in the solid state. The number of available dipeptide structures is large enough to permit meaningful conclusions. The dipeptide molecules in the crystal structures can be broadly classified as extended or folded depending upon their conformations. The basic elements of dipeptide aggregation are different types of head-to-tail sequences and sequences involving hydrogen bonds with the peptide nitrogen atom as the donor, generated by periodic translations and 2₁ screw axes. Using these basic elements and the known geometrical preferences of hydrogen bonds, it is possible to construct several plausible idealized patterns, mostly two-dimensional, of dipeptide aggregation for extended as well as folded molecules. The patterns observed in crystal structures are in substantial agreement with these idealized patterns. Infinite hydrogen-bonded sequences of the type observed in dipeptide structures remain the basic elements of aggregation in the structures of higher peptides also. The present analysis shows that peptide aggregation in the solid state is controlled primarily by interactions involving main chain atoms. Also, despite the increased molecular flexibility of peptides in comparison with amino acids and the presence of additional hydrogen bonding groups in them, head-to-tail sequences remain the most important intrinsic feature not only of amino acid aggregation but of peptide aggregation as well.     

Molecular cloning, expression and characterization of three short chain alpha-neurotoxins from the venom of sea snake--Hydrophiinae Hydrophis cyanocinctus Daudin.

Three different genes named sn311, sn316 and sn285 were discovered by large-scale randomly sequencing the high quality cDNA library of the venom glands from Hydrophiinae Hydrophis cyanocinctus Daudin. Sequence analysis showed that these three genes encoded three different short chain alpha-neurotoxins of 81 amino acids, which contained a signal peptide of 21 amino acids and followed by a mature peptide of 60 amino acids. Amino acid comparison reveals that mature peptides of sn311 and sn316 are highly homologous, with the only variance at position 46, which is Lys46 and Ser46, respectively. Whereas the mature peptide of sn285 lacks the most conserved amino acids in short chain alpha-neurotoxins, Asp31 and Arg33. The coding sequences of three neurotoxins were cloned into a thioredoxin (TRX) fusion expression vector (pTRX) and expressed as soluble recombinant fusion proteins in E. coli. After purification, approximately 10 mg/l recombinant proteins with the purity up to 95% were obtained. These three recombinant proteins are designated as rSN311, rSN316 and rSN285, they have a molecular weight of 6.963, 6.920 and 6.756 kDa, respectively, which are similar to those predicted from amino acid sequences. LD50 values of rSN311, rSN316 and rSN285 are 0.0827, 0.095, and 0.0647 mg/kg to mice, respectively. Studies on effects of these recombinant proteins on neuromuscular transmission were carried out, and results indicate that they all can produce prompt blockade of neuromuscular transmission, but display distinct biological activity characteristic individually. The results from UV-circular dichroism (CD) spectra indicate that they share similar secondary structure compared to other identified alpha-neurotoxins, and no significant structural differences in these recombinant proteins are observed.