Characterization of a naturally processed MHC class II-restricted T-cell determinant of hen egg lysozyme

Compelling evidence indicates that T cells recognize complexes formed by major histocompatibility complex-encoded molecules and antigenic peptide fragments. This is based largely on the ability of small synthetic peptides to substitute for naturally processed antigen in stimulating T cells. Naturally processed fragments of exogenous antigen are thought to arise by limited proteolytic degradation of native antigen inside acidic compartments of antigen-presenting cells, but until now no physiologically processed antigen has been directly analysed. Here we report the characterization of physiologically processed antigen eluted from mouse class II major histocompatibility complex I-Ed molecules. The antigenic material corresponds to a previously described antigenic determinant of hen egg lysozyme (HEL 107-116) and has a relative molecular mass Mr of about 2,000. HPLC analysis identified at least two or three separate molecular species, suggesting limited, albeit significant, heterogeneity of naturally processed peptides. Finally, under our experimental conditions, it was calculated that a substantial proportion (10-40%) of I-Ed molecules were occupied by these HEL-derived antigenic determinants.     

Sharing of an idiotypic marker by monoclonal antibodies specific for distinct regions of hen lysozyme

Idiotypes have been defined serologically as variable-region markers present on unique subsets of antibody molecules. Most studies involving myeloma proteins and antibody responses in inbred mice have indicated that idiotypy is closely related to antigenic specificity. However, indirect evidence suggests that idiotypy can sometimes be dissociated from specificity. In the response to the small monomeric protein, hen egg-white lysozyme (HEL), previous results demonstrated that 70--95% of the anti-HEL antibody found in sera of primed and boosted mice is specific for a particular region of HEL and bears a predominant idiotype (IdX-HEL). In this report, hybridoma anti-HEL antibodies tested with well-characterized peptide fragments of HEL show that the IdX-HEL marker can be found on antibodies of completely distinct antigen specificities. Thus, a mode of recognition other than antigenic recognition probably plays a major role in the immune response to HEL.     

固定化HRP海藻酸钙/壳聚糖微球催化水溶性导电聚苯胺的合成与表征

以海藻酸钙/壳聚糖微球为载体、用戊二醛共价交联固定于微球表面的辣根过氧化物酶(HRP)催化合成水溶性导电聚苯胺。考察了酶的固定化效果、负载率、比活力、贮存稳定性及酶促聚合特性,并对酶促聚合产物进行了表征。结果表明:共价交联微球固定化HRP可有效地用于水溶性导电聚苯胺的模板导向合成。     

Detection and characterization of a folding intermediate in barnase by NMR

Protein engineering is being developed for mapping the energetics and pathway of protein folding. From kinetic studies on wild-type and mutant proteins, the sequence and energetics of formation of tertiary interactions of side chains can be mapped and the formation of secondary structure inferred. Here we cross-check and complement results from this approach by using a recently developed procedure that traps and characterizes secondary structure in intermediate states using 1H NMR. The refolding of barnase is shown to be a multiphasic process in which the secondary structure in alpha-helices and beta-sheets and some turns is formed more rapidly than is the overall folding.     

共价有机骨架/碳纳米管复合材料中锂离子吸附与传输特性的分子模拟

利用分子模拟方法对共价有机骨架 (covalent organic framework, COF)/碳纳米管(carbon nanotube, CNT) 复合材料 COF@CNT 中锂离子 (Li$^{+})$ 的吸附与传输特性开展研究, 明确了 Li$^{+}$ 的吸附位点与吸附顺序, 得到了相应的吸附能, 并观察 COF@CNT 的表观形貌变化. 当达到饱和吸附状态时, COF@CNT 的体积变化率仅为 0.25, 平均电压保持在 2.00 V 以上, 而理论容量则高达 1 402.47 mAh/g. 此外, Li$^{+}$ 在 COF@CNT 内部的电导率大于其在单纯 CNT 中电导率的实测值. 模拟结果可为此类体系的实际应用提供理论基础.     

A strategy to obtain a high-density and high-strength zirconia ceramic via ceramic injection molding by the modification of oleic acid

Despite its unique high efficiency and good environmental compatibility, the water-soluble binder system still encounters problems achieving a desired sintered part via ceramic injection molding because of the poor compatibility and the powder-binder segregation between ceramic powders and binders. The objective of this study was to obtain a sintered part with excellent properties by introducing a small quantity of oleic acid to the surface of zirconia powders before the mixing process. As opposed to many previous investigations that focused only on the rheological behavior and modification mechanism, the sintering behavior and densification process were systematically investigated in this study. With the modified powders, debound parts with a more homogeneous and smaller pore size distribution were fabricated. Also, a higher density and greater flexural strength were achieved in the sintered parts fabricated using the modified powders.     

Architecture of Star-block Copolymers Consisting of Triblock Arms via a N,N-diethyldi-thiocarbamate-mediated Living Radical Photo-polymerization and Application for Nanocomposites by Using as Fillers

1 Results Highly branched poly(methyl methacrylate) (PMMA) stars were prepared by one-pot approach based on N,N-diethyldithiocarbamate-(DC) mediated living radical photo-polymerization.Soluble alternating hyperbranched microgel formation was initiated fast with preferential consumption of inimer 4-vinylbenzyl N,N-diethyldithiocarbamate (VBDC) and 4,4′-bismaleimidediphenylmethane (BMIM) in the presence of an excess of methyl methacrylate (MMA),PMMA arms could then grow from DC groups of microgel as macro...