福建大头蛙抗癌多肽FJ-2945抗肿瘤活性研究

探索本课题组自主发现的天然抗肿瘤多肽FJ-2945对肝癌细胞Hep3b增殖、迁移的影响并初步明确其作用机制.通过CCK8与RTCA实验检测FJ-2945对细胞增殖能力的影响;采用Transwell与划痕实验分析FJ-2945对于Hep3b迁移能力的影响;利用流式细胞分析法检测FJ-2945对Hep3b细胞周期的影响;最后通过qRT-PCR与免疫印迹实验检测FJ-2945对Hep3b细胞增殖、迁移相关因子在转录水平与蛋白水平的影响.与对照组相比,FJ-2945显著抑制Hep3b细胞的增殖与迁移能力,并促进Hep3b细胞凋亡.实验组中的Skp2蛋白含量显著降低,最终抑制Hep3b细胞增殖与迁移能力.由此说明多肽FJ-2945可以作为潜在的药物,通过靶向Skp2抑制肝癌细胞Hep3b增殖、迁移等过程,发挥抗肿瘤作用.     

外界因素和食品内部环境变化对Brevilaterin抗菌特性的影响

为探讨Brevibacillus laterosporus产的抗菌肽Brevilaterin的抗菌特性,考察了不同外界因素对其抗菌活性的影响,重点研究了食品内部环境变化与其抗菌作用的关系。研究结果表明:B revilaterin的抗菌活性几乎不受所选金属离子、乳化剂(除大豆磷脂外)、增稠剂、酶、高浓度蔗糖和反复冻融处理的影响,稳定性良好。随着食品内部温度、pH值和渗透压的改变,Brevilaterin对受试菌S.aureus、L.monocy.togenes、M.luteus、Paeruginosa、L.lactis和H.alkalicola的抗菌作用规律均发生显著变化,主要变化为:相比于受试菌生长最适温度(37℃)时的作用效果,4℃下Brevilaterin对M.luteus的最小抑菌浓度(MIC)和最小杀菌浓度(MBC)均降至1/8,10℃下Brevilaterin对P.aeruginosa、L.monocytogenes和S.aureus的MIC和MBC均降至1/4～1/2。相比于菌株生长最适pH值(6～7)时的作用效果,pH值为2时,Brevilaterin对L.lactis的MIC和MBC均降至1/2;pH值为8～9时,Brevilaterin对S.aureus的MIC和MBC均降至1/2;同样,pH值为7时,Brevilaterin对H. alkalicola的MIC和MBC均降至pH值为11(最适pH)时的1/4。相比于常压时的作用效果,高渗条件下Brevilaterin对S.aureus的MIC和MBC值均降至1/2。因此,当食源性致病菌的生长条件偏离其最适条件时,Brevilaterin能表现出更强的抗菌作用,而此时的MIC和MBC均可降至最适条件下的1/8～1/2。Brevilaterin不仅能稳定发挥其抗菌作用,而且能随着食品内部环境的变化表现出不同的规律,这可为其未来在食品防腐中的应用提供更科学的指导。     

蛙皮多肽抗生素的研究进展

蛙皮多肽抗生素(peptide antibiotics)是由两栖动物皮肤分泌的,有抗菌、抗癌作用的多肽,广泛存在于两栖动物的皮肤分泌物中.由于具有抗菌谱广、种类多、不易产生耐药性等优点,其应用已涉及到医药工业、食品工业等领域,应用前景广阔.从蛙皮多肽抗生素的分类、分子结构与功能、作用机制、生物学活性、化学修饰和基因工程方面概述了其研究现状与进展.     

新生肽链折叠的格子模型

由放置在简立方子上的１２５个以单位键长联接的残基模拟肽链，残基分为亲水和疏水两类．考虑每对非键联接的空间相邻疏水残基间相互吸引．新生肽链的折叠由两种算法模拟：生长算法模拟新生肽链的生长过程，类似于动力学生长行走（ＫＧＷ）．折叠算法采用Ｍｅｔｒｏｐｏｌｉｓ算法．在肽链生长过程中，两种算法交替使用，一旦生长完毕则只使用折叠算法．对３０个随机序列和４个真实蛋白序列的模拟结果表明，生长完毕时，即经过约１０３步模拟，肽链就已处于一种能量较低的状态，其后的折叠较缓慢，再经过约１０５模拟，无明显变化．Ｋａｒｐｌｕｓ小组的模拟结果表明，２７肽须经１０７步才能达到全局极小，这与蛋白体内折叠时标相差很多．提出ｒｏｂｕｓｔ极小的概念取代全局极小来描述蛋白质的生物活性状态．一个ｒｏｂｕｓｔ极小由一组能量足够低的、动力学可及的、几何结构相似的极小组成，系统进入ｒｏｂｕｓｔ极小就不会因热涨落而跃出．一个序列一般有多个ｒｏｂｕｓｔ极小，具体折叠到哪个则与折叠途径有关，据此提出将序列结构特异性推广为序列一途径一结构特异性．     

Confirmation of the structure of nisin and its major degradation product by FAB-MS and FAB-MS/MS

Summary FAB-MS has been applied to the analysis of a nisin complex and FAB-MS and FAB-MS/MS data from the major component used to provide confirmation of the amino sequence and positions of the sulphur-bridged rings in these highly modified peptides.     

Pre-and post-natal ontogeny of neutral endopeptidase 24-11 (‘enkephalinase’) studied by in vitro autoradiography in the rat

Neutral endopeptidase (NEP, enkephalinase, CALLA) which is present in various neural and non-neural tissues, is able to cleave a variety of regulatory peptides. The distribution of NEP has been studied during rat pre-and post-natal development by autoradiography after in vitro binding of the tritiated inhibitor [³H]HACBO-Gly to whole-body and organ sections. In the central nervous system (CNS), where the presence of NEP has been related to the termination of the action of enkephalins, the external layer of the olfactory bulbs is the only structure prominently labeled before birth. Other CNS structures rich in NEP in the adult, such as the nigrostriatal tract, are progressively labeled after birth. Outside the CNS, the progressive appearance of NEP in the kidney, the lungs and the salivary glands suggests its concomitant involvement in adult physiological functions, including fluid balance control, possibly by cleaving the atrial natriuretic peptide (ANP) and other peptides. On the other hand, transient or enhanced expression of NEP is observed during the development of several organs such as the sensory organs, the heart and the major blood vessels, the intestine, the bones and the genital tubercle. In addition to the still incompletely known physiological functions of the enzyme, the developmental pattern of its expression in several tissues strongly suggests a modulatory role for NEP in the ontogeny of a large number of organs.     

Kinetics of chemo-attraction of polymorphonuclear leukocytes towards N-formyl peptide studied with a novel polycarbonate (Nuclepore) membrane in the Boyden chamber

Summary The motile responses of human polymorphonuclear leukocytes (PMN) to N-formyl-methionyl-leucyl-phenylalanine (FMLP) in the Boyden chamber using a new sparse-pore polycarbonate membrane (pores 3 m in diameter and occupying 0.1% of surface area) were compared with those demonstrated by using a standard polycarbonate (Nuclepore) filtration membrane (pores 3 m in diameter and occupying 5% of surface area). Motility of PMN in gradients of FMLP using the new membrane was not influenced by chemokinetic effects of the factor, and the background migration of the cells was minimal. However, motility of PMN in gradients of FMLP using the standard membrane was found to be influenced by chemokinetic effects of the chemotactic factor, and the background or control migration (in the absence of chemotactic factor) of the cells was substantial. Greater directional migration of PMN according to steepness of the gradient of chemotactic factor was demonstrated with the use of the new membrane. The new membrane may be of considerable value in the further study of the chemotactic responses of PMN.     

化学合成十三肽及其副产物液质联用分析

利用反相高效液相色谱(RP-hplc)与电喷雾质谱(ESI-MS和MS/MS)联用技术直接分析用芴甲氧羰基(Fmoc)固相多肽合成方法手工偶联合成的一个十三肽(Lys-Lys-Glu-Ser-Asp-Phe-Leu-Met-Phe-Val-Tyr-Leu-Val，Mr 1617．8)粗产品，以探索RP-HPLC/ESI-MS和MS/MS在固相多肽合成产物分析和副反应机制研究中的应用．RP-HPLC结果显示：合成粗产物中含有1个主成分，2个次要成分和多个微量成分；与之联用的电喷雾质谱同步准确地测定出各成分的相对分子质量(m／z)并自动对各主要成分的化学结构进行了串联质谱分析．结果证明，粗产物中的主成分即为目标十三肽，另外几个主要副产物为十三肽的残缺肽或氧化肽．对色谱和生物质谱联用技术分析合成多肽的意义和副产物形成的可能机制进行了讨论．     

大鼠骨组织蛋白质组样品提取方法的建立

蛋白质组学是目前研究的重要热点．该拟建立大鼠骨组织蛋白质样品提取的最佳方法．用于双向电泳分离．为进一步进行蛋白组学分析奠定基础．实验对3种不同方法制备的样本进行同一条件的二维电泳(2-DE)图谱．比较2-DE的结果．结果发现，丙酮沉淀法最佳．这些结果提示．只有结合骨组织成分特征与双向电泳的具体要求．选择恰当的样品提取液．采用合理的提取步骤，获得蛋白质样品，才能得到清晰高分辨率的电泳图谱，满足蛋白质组学分析需要。