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00 0 0 2 3聚乙二醇大分子化猪血红蛋白对其携氧特性的影响 [中 ]/洪民… //生物工程学报 .- 2 0 0 0 ,16 (1).- 2 2～ 2 6用ＰＥＧ共轭结合猪血红蛋白 (ｐＨｂ)以增大总分子量是延长它的血液循环系统中存留时间的有效方法。作为一种线性的亲水大分子 ,ＰＥＧ对ｐＨｂ的共轭会对它的携氧特性产生显著影响。研究了 ｐＨｂ处于不同空间构象 (脱氧的Ｔ构象或氧合的Ｒ构象 )、ＰＥＧ修饰程度的高低、修饰用ＰＥＧ的分子量的大小、有无别构效应调节剂等不同条件下ＰＥＧ修饰对 ｐＨｂ携氧能力的影响。进而又用了ＰＥＧ修饰已经用双 (3,5-二溴水杨…     

PEG修饰的辣根过氧化物酶及其在非水介质中的性质

酶的化学修饰可以明显提高酶在有机相中的活力。通过氧化过氧化物酶（ＨＲＰ）的糖链后引入氨基再连接甲氧基聚乙醇（ＰＥＧ）５０００和在酶的肽链上连接ＰＥＧ５０００,发现ＨＲＰ多肽链上修饰后的酶在水相中的活力几乎没有变化,但通过氧化糖链连接ＰＥＧ的酶在水相中的活力下降近２倍。在甲苯及二氧六环含量较高的体系中,修和均呈上升趋势。特别在甲苯体系中两种修饰酶活力都比未经修饰的酶提高了近２倍。稳定性研究表明,不论     

氨基PEG化试剂的合成及其修饰能力的测定

分别用氰脲酰氯法及Ｎ－羟基丁二酰亚胺活性酯法合成了蛋白质的氨基ＰＥＧ化试剂ｍＰＥＧｃｃ和ｍＰＥＧ－ＧＳ,并研究了它们对蛋白质的修饰作用。在合成过程中,通过分析反应体系中微量水分的存在对ｍＰＥＧｃｃ合成效率的影响,及溶剂中小分子可活化杂质成分对ｍＰＥＧ－ＧＳ合成产物质量的影响,发现去水剂的存在,可使ｍＰＥＧｃｅ产率提高７倍;二氧六环优于ＤＭＦ,且二氧六环的预处理也很重要。同时,为了测定活化ＰＥＧ修饰蛋白质的效能,首次以ＢＳＡ为模型蛋白,建立起一种测定活化ＰＥＧ修饰能力的方法,应用此方法能直观而又准确地比较各种方法活化的ＰＥＧ对蛋白质的修饰能力,具有普遍的意义。     

氨基PEG化试剂的合成及其修饰能力的测定

分别用氰脲酰氯法及Ｎ－羟基丁二酰亚胺活性酯法合成了蛋白质的氨基ＰＥＧ化试剂ｍＰＥＧｃｃ和ｍＰＥＧ－ＧＳ,并研究了它们对蛋白质的修饰作用。在合成过程中,通过分析反应体系中微量水分的存在对ｍＰＥＧｃｃ合成效率的影响,及溶剂中小分子可活化杂质成分对ｍＰＥＧ－ＧＳ合成产物质量的影响,发现去水剂的存在,可使ｍＰＥＧｃｃ产率提高７倍;二氧六环优于ＤＭＦ,且二氧六环的预处理也很重要。同时,为了测定活化ＰＥＧ修饰     

蛋白质定点PEG化研究：97Cys－IFH－γ的巯基专—PEG修饰

蛋白质定点ＰＥＧ化研究：９７Ｃｙｓ－ＩＦＨ－γ的巯基专—ＰＥＧ修饰唐微,常远,徐　飞,郑仲承,刘新垣（中国科学院上海生物化学研究所,２０００３１）关键词人干扰素－γ;定点修饰;半胱氨酸目前进行的ＰＥＧ化反应,多是针对蛋白质肽链上自由末端氨基进行的,由...     

白细胞介素—2的PEG化

用自制的氨基ＰＥＧ化试剂ｒＩＬ－２进行化学修饰,研究了试剂浓度,溶液ｐＨ,反应时间间等与ＰＥＧ－ｒＩＬ－２产率及ＩＬ－２活性保持之间的关系,建立了一套获得稳定修饰度的ＰＥＧ－ｒＩＬ－２的方法,研究发现,反应时间跟修饰度关系不大;溶液ｐＨ对修饰度有一定的影响,中性ｐＨ以上反应都可进行;而试剂浓度直接决定修饰度的高低,过量越多,修饰度越高,而生物活性保留也越低;但低度修饰,对活性几乎没有影响,可保留活     

白细胞介素－2的PEG化

用自制的氨基ＰＥＧ化试剂ｒＩＬ－２进行化学修饰,研究了试剂浓度,溶液ｐＨ,反应时间等与ＰＥｃａ－ｒＩＬ－２产率及ＩＬ－２活性保持之间的关系,建立了一套获得稳定修饰度的ＰＥＧ－ｒＩＬ－２的方法。研究发现,反应时间跟修饰度关系不大;溶液ｐＨ对修饰度有一定的影响,中性ｐＨ以上反应都可进行;而试剂浓度直接决定修饰度的高低,过量越多,修饰度越高,而生物活性保留也越低;但低度修饰,对活性几乎没有影响,可保留活性在９５％左右。     

氧化棉子糖分子内交联猪血红蛋白对其结构功能的影响

用高碘酸盐氧化法制得氧化开环棉子糖,并用它分别修饰处在氧合及脱氧构象的猪血红蛋白得到两种不同的修饰衍生物。与天然蛋白质相比,两种修饰后的猪血红蛋白衍生物均具有明显的抗α２β２四聚体解聚的特性。经ＳＤＳ－ＰＡＧＥ和反相ＨＰＬＣ分析发现这两种修饰衍生物均为分子内交联产物,而且交联都发生于２个β亚基之间,两种交联产物的紫外－可见光谱没有明显差别,但在相同浓度下,脱氧构象下被修饰蛋白质的荧光发射光强度明显     

天花粉蛋白的定点聚乙二醇修饰

用一种定点修饰天花粉蛋白（ｔｒｉｃｈｏｓａｎｔｈｉｎ,ＴＣＳ）的方法,将聚乙二醇（ＰＥＧ）偶联到预先选定的位点．利用ｎＴＣＳ无半胱氨酸（Ｃｙｓ）残基这一特点,通过定点突变将一个Ｃｙｓ残基引入ＴＣＳ以取代第７位的丝氨酸（Ｓｅｒ）残基．然后,与巯基反应的ＰＥＧ－ｍ ａｌｅｉｍ ｉｄｅ 即可偶联到新引入的Ｃｙｓ 残基上．经纯化得到均一的ＰＥＧ－ＴＣＳ复合物,在ＳＤＳ－ＰＡＧＥ上显示一条区带,表观分子量为３８ ｋＤ．复合物的体外致核糖体失活活性降低了６倍,但其体内引产活性与ｎＴＣＳ相同．定点ＰＥＧ修饰方法为改造ＴＣＳ提供了新途径．     

牛肾上腺皮质LDL受体的纯化和抗体的制备

牛肾上腺皮质ＬＤＬ受体经Ｔｒｉｔｏｎ Ｘ－１００增溶,ＤＥＡＥ３２离子交换柱和ＬｐＢ Ｓｅｐｈａｒｏｓｅ亲和柱层析,在ＳＤＳ－ＰＡＧＥ中有三条区带,分别在原点;Ｍｒ １６０ｋＤ;Ｍｒ１２５ｋＤ处。进一步用８％ＳＤＳ－ＰＡＧＥ纯化三个区带的蛋白质分别免疫新西兰大白兔所得的抗体,应用免疫印迹和ＥＣＬ非同位素标记法可对牛肾上腺皮质和人皮肤纤维细胞膜上的ＬＤＬ受体进行测定。     

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.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细