多肽酰胺化酶的结构与功能

C端酰胺化是许多神经内分泌多肽重要的翻译后加工过程,是在酰胺化酶的催化下分两步进行的,PHM和PAL分别催化这两步反应.PHM由两个结构相似的结构域组成,每个结构域均为九链β折叠组成的三明治样结构,分别由三个His或两个His和一个Met螯合一个Cu组成活性中心.在一个反应周期中,两个Cu分别独立地与抗坏血酸和分子氧发生单电子传递的氧化还原反应,最后完成多肽底物的α-碳的羟化反应.     

紫膜表面电荷数的测量

以CAT₁₂为自旋探针,用ESR自旋标记法测量了不同表面pH时酰化前后紫膜表面负电荷密度,以酰化所屏蔽的表面电荷数为标准,计算了表面pH4-11时单位菌紫质紫膜两侧的总负电荷数.结果表明:表面pH5-9时为9,表面pH≥10及表面pH < 5时增大.结果有力支持了膜表面5个二价阳离子结合位点的模型.     

共价连接的多肽酶联免疫测定法的研究

采用紫外线照射及戊二醛活化处理聚苯乙烯酶标板后再包被八肽胆囊收缩素（CCK-8）,以此为基础进行酶联免疫吸附试验（ELISA）,通过不同的洗涤过程对CCK-8与酶标板相互作用的性质进行研究.结果表明,该包被方法可使CCK-8通过共价交联的方式稳定地结合于固相载体上,该方法适用于不同来源的酶标板,处理后的酶标板性质稳定,可储存使用,测定的批内及批间变异系数分别为4.75%和7.80%,方法稳定可靠,重复性好,便于推广应用.     

酶解法制备草鱼抗氧化多肽工艺的建立

目的:筛选优化合适的可用于水解草鱼蛋白制备活性多肽的蛋白酶制剂及其工艺.方法:选取不同特性来源的商品化蛋白酶制剂与实验室分离的枯草蛋白酶BPN,对比分析它们在水解草鱼蛋白过程中的水解度变化,及其酶解产物的抗氧化活性.结果:大多数蛋白酶在水解反应最初的60min内,水解度迅速增加,之后2h内曲线变化不大.其中细菌来源的水解蛋白酶水解能力最强,其2h水解产物水解度可达15.17％;木瓜蛋白酶水解产物的抗氧化活性较强,经测定其DPPH清除能力为96.24％.结论:不同特性的蛋白酶水解草鱼蛋白的水解速度和产物的活性成分具有明显差异,总的来说,木瓜蛋白酶在草鱼蛋白加工中制备活性多肽是一个比较理想的选择.     

酶水解制备花生粕多肽工艺的优化

目的：优化研究花生粕制备多肽的工艺。方法：采用酶法水解提取多肽、用总蛋白试剂盒（TP）双缩脲比色法在540nm处测定其含量。结果：用木瓜蛋白酶水解花生粕蛋白得到多肽的最佳工艺条件为：加酶量6 300u/g原料、温度45℃、底物浓度10%、酶水解时间5h。     

DNA数进制与酶催化的信息传递

通过对DNA中四种碱基进行排列组合的计算,发现DNA是一个多种的数进制系统;20进制信息约占全部数进制信息的4.515%;每种数进制信息由它的产生方式而表现出不同的调控功能;相同的DNA片段用不同的读取方式,可以得到不同的数进制信息.从能量守恒定理和小分子RNA具有酶催化功能推断,酶的催化机制是一个信息传递的过程.     

蜀柏毒蛾核型多角体病毒结构多肽及基因组酶切分析

对蜀伯毒蛾核型多角体病毒（Ｐａｒｏｃｎｅｒｉａ ｏｒｉｅｎｔａ Ｎｕｃｌｅａｒ ｐｏｌｙｈｅｄｒｏｖｉｒｕｓ,简称ＰａｏｒＮＰＶ）形态结构、结构多肽、限制内切酶图谱等特性进行了研究。采用不连续系统垂直板ＳＤＳ－ＰＡＧＥ分析了ＰａｏｒＮＰＶ的多角体蛋白、病毒粒子结构多肽。应用５种限制性内切酶对ＰａｏｒＮＰＶ基因组ＤＮＡ进行了酶切分析。结果表明：经热处理的多角体蛋白仅有一条带,分子量为３１．５ｋＤ,不     

抗溶葡萄球菌酶N端合成多肽抗体的制备与鉴定

为了制备抗溶葡萄球菌酶N端合成多肽抗体,合成了溶葡萄球菌酶(lysostaphin)分子的3-13位的11个氨基酸的多肽(THEHSAQWLN),并利用戊二醛双功能试剂将人工合成多肤成功地与KLH进行偶联.免疫新西兰兔制备抗lysostaphin合成多肽的抗体,并经亲和层析进行了纯化.对此抗体进行鉴定的结果表明,抗溶葡萄球菌酶合成多肽抗体可与重组溶葡萄球菌酶分子发生特异性反应,并可用于蛋白免疫印迹.该抗体的制备为使用亲和层析纯化溶葡萄球菌酶提供了有用的配基.     

蜀柏毒蛾核型多角体病毒结构多肽及基因组酶切分析

对蜀柏毒蛾核型多角体病毒(Parocneria orienta Nuclear polyhedrovirus,简称PaorNPV)形态结构、结构多肽、限制性内切酶图谱等特性进行了研究.采用不连续系统垂直板SDS-PAGE分析了PaorNPV的多角体蛋白、病毒粒子结构多肽.应用5种限制性内切酶对PaorNPV基因组DNA进行了酶切分析.结果表明:经热处理的多角体蛋白仅有一条带,分子量为31.5 kD,不经热处理的多角体蛋白有三条带,分子量分别为31.5 kD、29.1 kD、28.6 kD;病毒粒子包含有25种结构多肽,分子量范围在17.6-114.6 kD之间.PaorNPV DNA经BamH I.EcoR I、HindⅢ、Pst I和Xho I酶切分别产生9、12、12、12和14条片段.基因组大小平均为124.6 kb.     

牛胰多肽（BPP）二级结构的红外光谱和圆二色谱分析

牛胰多肽（ｂｏｖｉｎｅｐａｎｃｒｅａｔｉｃｐｏｌｙｐｅｐｔｉｄｅ,ＢＰＰ）是胰脏分泌的一种含有３６个氨基酸的多肽［１］,ＢＰＰ能预防和治疗由胆酸盐诱发的大鼠急性胰腺炎,具有细胞保护作用。本文用傅里叶变换红外光谱（ＦＴ－ＩＲ）和圆二色谱（ＣＤ）,对ＢＰＰ在水溶液中的二级结构进行了研究。两种方法的分析结果互相补充,进一步确定了ＢＰＰ在溶液状态的二级结构。本研究为进一步探讨ＢＰＰ抑制膜融合的机理打下了基础。     

甘露醇对Lowry法测定冻干注射用胸腺肽中多肽含量的影响

用Ｌｏｗｒｙ法测定冻干注射用胸腺肽中多肽含量时,由于冻干前所加赋形剂甘露醇的干扰,其测定结果明显偏高（Ｐ＜０．０００５）。本文经试验证明,用等量于检品中的甘露醇作空白对照,可以消除这种干扰。     

多肽抗体检测原发性肝癌血清标志物ELISA方法的建立及应用

血清多肽是癌症诊断信息的重要来源,建立、优化了检测多肽标志物的直接ELISA法,并应用于肝癌血清中的多肽标志物的检测。制备及纯化针对多肽标志物Pep5的单克隆抗体并进行辣根过氧化物酶标记,用其建立检测相应抗原的直接ELISA法。方法线性范围为1.5-20 ng/mL,检测限为1.24 ng/mL;标准品批内及批间CV分别小于3.66%及4.89%,血清样本批内及批间CV分别小于11.69%及18.18%;线性范围内(9、12和15 ng/mL)的回收率分别为98.98%,99.61%和101.58%。应用该方法共检测160例正常血清、104例肝硬化及156例肝癌患者血清,正常组与肝硬化组及肝癌组间差异显著(P<0.001),Pep5诊断肝癌的敏感性和特异性分别为80.8%和96.2%。同时检测94例HCC血清中的AFP和Pep5,AFP检出率为63.8%,Pep5检出率为90.4%,AFP联合Pep5检测时,能将HCC的检出率提高至94.7%。     

Polypeptide Elongation Factors of the Developing Chick Brain

Abstract: The polypeptide elongation factors (EF-1_L, EF-1_H, and EF-2) of the developing chick brain were separated and purified by means of a combination of gel chromatographic methods. The molecular weight of EF-1_H of the chick brain ranged from 5 to 10 × 10⁵, and was different from that of the chick liver (about 7 × 10⁵). The molecular weight of other purified factors was about 5 × 10⁴ for EF-1_L. and 9.4 × 10⁴ for EF-2. High activities of polyphenylalanine (poly-Phe) synthesis per mg protein in the developing chick brain were observed between the 3rd embryonic week and the 1st post-hatch week and declined afterwards. On the other hand, the levels of both EF-1 and EF-2 per mg protein in the brain were observed to be high in an early embryonic stage, gradually declining afterwards to the adult level. The brain EF-1_L was a major component of EF-1 in an early embryonic stage, while EF-1_H became recognizable in the 3rd embryonic week. Moreover, the EF-1_H activities were found to be more than double with regard to the binding reaction and to be more than 10-fold as active in respect to poly-Phe synthesis in comparison with the activities of EF-1_L. It is proposed that the brain EF-1_H could be due to aggregates consisting of EF-1_L, a stimulatory factor, and other components.     

Polypeptide Changes in Cotyledons During Cucunlber Seedling Development and Chilling Acclimation

The changes of chilling resistance and polypeptide pattern during cucumber (Cucumis sativus L. ) seedling development and during chilling acclimation in light (CAL) and chilling acclimation in dark(CAD) have been studied. The results showed that the chilling resistance decreased gradually during seedling development ,CAL could enhance chilling resistance but CAD made the seedlings more sensitive to chilling temperature Two dimension PAGE study showed that during 6--12 days old seedling development some polypeptides disappeared and some appeared . CAL and CAD had different effects on those polypeptides. Both CAL and CAD induced a 58.0 kD polypeptide. There might be cooperation among several genes during chilling acclimation. Chilling endurance obtained from acclimation is based on the integration of metabolism correlated with development.     

Impact of the Enzyme Flexibility on the Enzyme Enantio-selectivity in Organic Media Towards Specific and Non-specific Substrates

A rationale is presented as to why the enantioselectivity of enzymes in dry organic media towards specific substrates is increased when the enzyme flexibility is increased. This is outlined for serine proteases towards N -acetyl-amino acid esters. The reasons why this relationship does not hold in the case of non-specific substrates are discussed.     

Impact of the Enzyme Flexibility on the Enzyme Enantio-selectivity in Organic Media Towards Specific and Non-specific Substrates

A rationale is presented as to why the enantioselectivity of enzymes in dry organic media towards specific substrates is increased when the enzyme flexibility is increased. This is outlined for serine proteases towards N -acetyl-amino acid esters. The reasons why this relationship does not hold in the case of non-specific substrates are discussed.     

不同生境下铺地黍叶片蛋白质合成的比较

铺地黍是广泛分布在热带与亚热带的一种多年生禾草,可作为牧草及草坪植物,常见于农田、水湿地及海边,对盐度、干旱有较强的适应能力,是厦门岛滨海沙生植被的主要种类之一［１］。迄今尚未见对其耐盐（旱）机理的研究报道。本文通过比较铺地黍在不同生境下蛋白质组分的变化,从一个侧面探讨铺地黍的耐盐（旱）机理。１　材料和方法滨海沙生的铺地黍（ＰａｎｉｃｕｍｒｅｐｅｎｓＬ．）采自福建省厦门岛（东经１１７°５３′～１１８°２５′,北纬２４°２３′～２５°５５′）东海岸。该处沙滩地势平缓,坡度２０～２５度,盐度１．５％…     

多肽铬螯合物对糖尿病小鼠肝脏蛋白质表达的影响

目的:研究多肽铬螯合的对糖尿病小鼠肝脏蛋白质表达的影响,探讨其治疗糖尿病的机理.方法:通过腹腔注射四氧嘧啶建立糖尿病小鼠模型.将小鼠分为正常组、模型组和胶铬组,胶铬组以灌胃方式加入多肽铬螯合物;以光镜及HE染色观察三组小鼠肝脏形态及组织学的变化,采用SDS-PAGE实验和非SDS-PAGE检测三组小鼠肝脏蛋白质表达.结果:光镜及组织学观察结果显示多肽铬螫合物可以有效地减轻四氧嘧啶对肝细胞造成的损伤.模型组肝脏25kDa-35kDa之间的某种蛋白表达升高而多肽铬螯舍物可以降低此种蛋白的表达,初步推断这种蛋白质为SOD.结论:多肽铬螯合物能够通过降低四氧嘧啶造成的肝脏中抗氧化有关的蛋白质代偿性升高而祈祷保护肝脏的作用,是一种新型的治疗糖尿病所致的肝损伤的活性物质.     

Comparison of Polypeptide Synthesis in Leaf of Panicum repens Grown in Different Habitats

he polypeptide synthesis in leaf of Panicum repens L. grown naturally in different habitats was analyzed using SDS-PAGE. Preliminary experiment indicates that the overall changes in polypeptide synthesis were relatively small, but the synthesis of a 30.6 kD polypeptide was enhanced in P. repens grown in sandy beach (salinity 1.5% ～ 3.0 % ) and that of a 130 kD pelypeptide markedly decreased. However, the content of the 130 kD protein increased in P. repens grown in sandy farmlands (salinity 0.1%～0.3% ), especially in water marsh (salinity 0.3 % ～0.5 % ).