糖蛋白的结构与功能

糖蛋白是由寡糖和多肽链共价修饰连接而形成的一类重要生理活性物质,它广泛存在于细胞膜,细胞间质,血浆以及粘液中,糖蛋白中的糖链在维持蛋白质稳定,抵抗蛋白酶水解,防止抗体识别及参与肽链在内质网的拆叠启动等方面发挥着重要作用,具有开关和调谐功能,激素功能,胞内转运功能,保护和促进物质吸收,参与血液凝固与细胞识别等,对于增殖的调控,受精,发生,分化以及免疫等生命现象,起着十分重要的作用。     

糖蛋白的研究进展

糖蛋白是由糖链与多肽链以多种形式共价修饰而形成的一类重要生理活性物质.糖蛋白在生物体内种类繁多,分布广泛,具有重要的功能.糖蛋白的性质及功能和糖链的结构有关,因此糖蛋白中糖链的结构及作用机制研究成为生物学基础理论的课题之一.就近年来糖蛋白研究中糖蛋白样品的提取分离、糖链释放及结构分析的技术方法及研究领域作了简要介绍.     

用过碘酸氧化试验鉴定单抗抗糖表位特性

过碘酸在酸性条件下能氧化糖蛋白中糖的连羟基而不改变多肽链结构。将这一特性与ELISA或免疫印迹试验结合起来建立了检测单抗是否抗糖表位的方法。     

油酸对消炎痛引起的胃粘膜损伤大鼠胃粘液分泌的影响

本工作研究油酸对消炎痛引起胃粘膜损伤大鼠胃粘液分泌的影响。胃粘液测定采用阿尔新蓝(Alcian blue)与胃液中糖蛋白结合的方法。将1.0ml 油酸注入到结扎幽门的大鼠空肠内,就可引起胃壁粘液及游离粘液分泌量的明显增加。以0.25、0.5和1.0ml 油酸注入到不结扎幽门的大鼠空肠内,也能显著增加胃壁粘液分泌,保护胃粘膜。这两种作用表现着剂量依赖关系。不论以油酸灌胃或注入空肠、回肠,都能明显增加胃壁粘液量,而灌胃的作用比注入肠内更明显。以1.0ml 30%甘油、0.1%乙酸及1/15N HCl 分别注入空肠,都不能刺激胃壁粘液的分泌。上述结果表明,油酸具有刺激胃粘液分泌的作用。因此,加强胃粘液分泌可能对粘膜起到屏障作用,这是油酸保护胃粘膜损伤的机制之一。     

性激素对大白鼠胃粘液分泌的影响

通过雄、雌性大鼠去势,怀孕鼠,以及肌肉注射性激素的方法,观察内,外源性激素对胃粘液分泌的影响,采用Ａｌｃｉａｎ ｂｌｕｅ与胃液和胃壁粘液中糖蛋白结合的方法进行胃粘液测定,结果表明：雄、雌鼠胃粘液分泌无性别差异,去势夺雄、雌鼠胃粘液分泌无明显影响;怀孕鼠胃粘液分泌增加,丙酶睾酮对去势雄、雌鼠胃粘液分泌无影响,而戊酸雌二醇和孕酮可增加胃粘液分泌,提示：怀孕鼠胃粘液分泌的增加可能与雌激素和孕激素分泌增多     

细菌对肉鸡肠粘液的粘附作用

研究两歧双歧杆菌、嗜酸乳杆菌、禽大肠杆菌O78、大肠杆菌 ATCC 25922、鸡白痢沙门氏菌和鼠伤寒沙门氏菌与肉鸡不同部位肠粘液糖蛋白的粘附性能,探讨两歧双歧杆菌和嗜酸乳杆菌对所试病原菌的抗粘附作用。结果表明：在不同的肠道部位,两歧双歧杆菌、嗜酸乳杆菌、鸡白痢沙门氏菌和鼠伤寒沙门氏菌与肠粘液糖蛋白均有不同的粘附作用,而禽大肠杆菌O78、大肠杆菌 ATCC 25922在各肠段粘液上的粘附性能则相近;在相同的肠道部位,所试益生菌的粘附能力大于病原菌;两歧双歧杆菌和嗜酸乳杆菌对所试病原菌的粘附有不同的阻断作用,同时二者有时还存在互补抗粘附作用。     

GDDR 转基因小鼠的基因表达鉴定及功能初步分析

目的:对构建的胃癌相关下调基因GDDR(Gastric Dramatic Down-related)转基因小鼠进行鉴定及功能初步检测,为深一步研究GDDR的生物学功能提供可靠的动物模型。方法:对GDDR转基因和野生对照(未经过基因修饰)小鼠胃组织使用实时定量PCR检测其基因转录情况,western blot和免疫组化检测其组织蛋白表达水平及表达部位。通过胃组织进行糖原染色和胃粘膜表面主要糖蛋白MUC5AC行免疫组化染色对小鼠表型进行初步分析。结果:实时定量PCR、western blot和免疫组化结果均显示在GDDR转基因小鼠中胃粘膜GDDR的表达水平明显高于野生组。糖原染色结果显示GDDR转基因小鼠的粘液分泌及粘液厚度高于正常对照组,糖蛋白MUC5AC的表达也显著强于野生组。结论:经过鉴定GDDR转基因小鼠的外源性基因GDDR得到成功表达。通过对GDDR转基因小鼠表型的初步分析,提示GDDR可能参与胃粘膜粘液层的组成和增加粘液分泌从而发挥着保护胃粘膜的作用。     

浅谈糖蛋白

糖蛋白是指糖和蛋白质间,以蛋白质为主,其一定部位以共价键与若干糖分子链相连而构成的分子。糖蛋白广泛存在于生物体内,包括许多酶、大分子蛋白质、激素、血浆蛋白、全部抗体、血型物质和粘液组分以及许多膜蛋白,是细胞质膜、细胞间质、血浆、粘液等的重要组成成     

乳铁蛋白分子结构及其抗菌机制

乳铁蛋白是一种单体糖蛋白,是哺乳动物非特异性免疫系统的第一道防线,具有防御微生物感染的功能。分析了乳铁蛋白氨基酸组成、多肽链折叠、铁结合结构、分子表面特性等与抗菌有关的分子结构。综述了乳铁蛋白抗微生物活性的作用机制,包括限制Fe3+利用,抑制细菌生物膜形成,与负电性生物大分子结合,降解细菌毒力因子以及阻止细菌入侵等。     

降钙素可抑制人胃癌KATOⅢ细胞的生长

除钙素(calcitonin)是一种对胃肠机能有广泛影响的激素,它对胃酸分泌有抑制作用,还可刺激灌流的大鼠胃释放生长抑素,它还可增加糖蛋白的合成,使粘液细胞的cAMP生成增加,表明对胃粘膜有重要保护作用。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Synthesis and antimicrobial studies of hydrazone derivatives of 4-[3-(2,4-difluorophenyl)-4-formyl-1H-pyrazol-1-yl]benzoic acid and 4-[3-(3,4-difluorophenyl)-4-formyl-1H-pyrazol-1-yl]benzoic acid

Microbial resistance to antibiotics is an unresolved global concern, which needs urgent and coordinated action. One of the guidelines of the Centers for Disease Control and Preventions (CDC) to combat antibiotic resistance is the development of new antibiotics to treat drug-resistant bacteria. In our effort to find new antibiotics, we report the synthesis and antimicrobial studies of 30 new pyrazole derivatives. These novel molecules have been synthesized by using readily available starting materials and benign reaction conditions. Some of these molecules have shown activity with MIC values as low as 0.78?µg/mL against four bacterial strains; Staphylococcus aureus, methicillin-resistant S. aureus, Bacillus subtilis, and Acinetobacter baumannii. Furthermore, active molecules are non-toxic to mammalian cell line.

     

Novel compounds with potent CDK9 inhibitory activity for the treatment of myeloma

Cyclin-dependent kinases (CDKs) and Polo-like kinases (PLKs) play key role in the regulation of the cell cycle. The aim of our study was originally the further development of our recently discovered polo-like kinase 1 (PLK1) inhibitors. A series of new 2,4-disubstituted pyrimidine derivatives were synthesized around the original hit, but their PLK1 inhibitory activity was very poor. However the novel compounds showed nanomolar CDK9 inhibitory activity and very good antiproliferative effect on multiple myeloma cell lines (RPMI-8226).