Specific binding of antigenic peptides to cell-associated MHC class I molecules

T lymphocytes recognize antigen in the form of peptides that associate with specific alleles of class I or class II major histocompatibility (MHC) molecules. By contrast with the clear MHC allele-specific binding of peptides to purified class II molecules purified solubilized class I molecules either bind relatively poorly or show degenerate specificity. Using photo-affinity labelling, we demonstrate here the specific interaction of peptides with cell-associated MHC class I molecules and show that this involves metabolically active processes.     

Structure of the detoxification catalyst mercuric ion reductase from Bacillus sp. strain RC607

Several hundred million tons of toxic mercurials are dispersed in the biosphere. Microbes can detoxify organo-mercurials and mercury salts through sequential action of two enzymes, organomercury lyase and mercuric ion reductase (MerA). The latter, a homodimer with homology to the FAD-dependent disulphide oxidoreductases, catalyses the reaction NADPH + Hg(II)----NADP+ + H+ + Hg(0), one of the very rare enzymic reactions with metal substrates. Human glutathione reductase serves as a reference molecule for FAD-dependent disulphide reductases and between its primary structure and that of MerA from Tn501 (Pseudomonas), Tn21 (Shigella), p1258 (Staphylococcus) and Bacillus, 25-30% of the residues have been conserved. All MerAs have a C-terminal extension about 15 residues long but have very varied N termini. Although the enzyme from Streptomyces lividans has no addition, from Pseudomonas aeruginosa Tn501 and Bacillus sp. strain RC607 it has one and two copies respectively of a domain of 80-85 residues, highly homologous to MerP, the periplasmic component of proteins encoded by the mer operon. These domains can be proteolytically cleaved off without changing the catalytic efficiency. We report here the crystal structure of MerA from the Gram-positive bacterium Bacillus sp. strain RC607. Analysis of its complexes with nicotinamide dinucleotide substrates and the inhibitor Cd(II) reveals how limited structural changes enable an enzyme to accept as substrate what used to be a dangerous inhibitor. Knowledge of the mode of mercury ligation is a prerequisite for understanding this unique detoxification mechanism.     

Characterization of the rough endoplasmic reticulum ribosome-binding activity.

The rough endoplasmic reticulum membranes of mammalian cells contain specific ribosome-binding sites. A purification to apparent homogeneity of a negatively charged protein (ERp180) of relative molecular mass 180,000 (180 K) was reported which was proposed to function as a rough endoplasmic reticulum ribosome receptor. We report here that ribosome-binding site activity quantitatively solubilized from rough endoplasmic reticulum membranes does not cofractionate with ERp180. By contrast, ribosome-binding site activity fractionates as a much smaller, positively charged protein.     

高校图书馆“学科馆员”制度的建立与馆员继续教育

针对目前高校图书馆高贵质人才匮乏的现状，论述了高校图书馆“学科馆员”制度建立的必然性及对“学科馆员”的高贵质要求，指出馆员的继续教育是培养“学科馆员”的主要人才保障，提出了“学科馆员”继续教育的内容及方式。     

永不消失的白螺号——访藏学大师东噶·洛桑赤列先生

东噶·洛桑赤列教授是享誉国际国内的藏学家，国家级专家，曾担任中国藏学研究中心副总干事和西藏社会科学院名誉院长等行政职务，先后任中央民族大学藏学院、西藏大学文学院教授。在他长期的坎坷人生经历中，由一名农奴成为著名的藏传佛教活佛，由一名俄让巴密宗师转变为接受马克思主义的教授，成为著述等身的大师级学者。先后经历过新旧社会的变革，新旧文化的熏陶，他的学术思想在无数磨砺中闪闪发光，他的天资在特殊的文化环境中释放出无穷的能量，他的人品、治学精神，在学术领域永无止境的追求探索的精神和他留下的20多部学术著作，已经成为中华民族一笔宝贵的文化遗产。文章根据1984年冬至1997年2月之阍陆续采访的记录（手稿），主要对东噶·洛桑赤列先生的人生历程、研究成果、学术观点、治学精神等方面的内容进行了摘编。     

稀土对2Cr13不锈钢夹杂物形态和耐腐蚀性能的影响

设计了不同含量的稀土2Cr13不锈钢,采用扫描电子显微镜观察了不锈钢中稀土夹杂物的形态,并用动电位扫描法对其进行了极化曲线的测试。