小鼠Lewis肺癌组织中层粘连蛋白受体的分离及其性质的研究

层粘连蛋白(Laminin,LN)是基膜(basement membrane)中的一种主要大分子糖蛋白。一些研究资料表明肿瘤细胞的浸润转移可能与LN有关。肿瘤细胞与LN的作用可能是通过细胞表面LN受体进行的。本文采用亲和层析法从小鼠Lewis肺癌组织中分离LN受体并对其理化性质进行研究。Lewis肺癌LN受体的表观分子量为70,000,还原后SDS电泳图为一条较宽的条带。氨基酸组成中疏水氨基酸占38％,苏氨酸、絲氨酸、门冬氨酸(包括门冬酰胺)占23.5％,通过硝酸纤维素膜片法用HRP-LN测定受体与LN的结合特性,证明具有配基结合专一性,饱和性及高亲和性(Kd=0.95×10~(-9)mol/L)。     

固定化酶的微环境效应—载体离子基团性质的影响

作者合成了阴离子型和阳离子型葡聚糖,以此为载体,用CNBr活化其剩余羟基,固定化了葡萄糖淀粉酶和葡萄糖异构酶。就离子型载体对固定化酶的蛋白载量、最适pH和热稳定性等的影响做了考察。发现固定化酶的蛋白载量不仅与载体的电性质有关,也与酶分子自身的电性质有关。当载体电性质与酶蛋白电性质相反时,固定化酶的蛋白载量增加,热稳定性提高、载体电性质与酶蛋白电性质相同时,固定化酶的蛋白载量不变或下降,其热稳定性不变。作者还发现当离子型载体孔度和体系缓冲液浓度一定时,酶分子能否进入多孔性载体内部,对其最适pH是否变化影响极大。若酶分子仅被连接在载体的外表层,其最适pH不发生变化,反之亦然。作者还观察到当多糖类载体引入氨基或羧基后,大大增强了其抵抗微生物侵蚀的能力。     

Sequence diversity within the argF, fbp and recA genes of natural isolates of Neisseria meningitidis: interspecies recombination within the argF gene

Studies of natural populations of Neisseria meningitidis using multilocus enzyme electrophoresis have shown extensive genetic variation within this species, which, it has been proposed, implies a level of sequence diversity within meningococci that is greater than that normally considered as the criterion for species limits in bacteria. To obtain a direct measure of the sequence diversity among meningococci, we obtained the nucleotide sequences of most of the argF, recA and fbp genes of eight meningococci of widely differing electrophoretic type (from the reference collection of Caugant). Sequence variation between the meningococcal strains ranged from 0-0.6% for fbp, 0-1.3% for argF, and 0-3.3% for recA. These levels of diversity are no greater than those found within Escherichia coli 'housekeeping' genes and suggest that multilocus enzyme electrophoresis may overestimate the extent of nucleotide sequence diversity within meningococci. The average sequence divergence between the Neisseria meningitidis strains and N. gonorrhoeae strain FA19 was 1.0% for fbp and 1.6% for recA. The argF gene, although very uniform among the eight meningococcal isolates, had a striking mosaic structure when compared with the gonococcal argF gene: two regions of the gene differed by greater than 13% in nucleotide sequence between meningococci and gonococci, whereas the rest of the gene differed by less than 1.7%. One of the diverged regions was shown to have been introduced from the argF gene of a commensal Neisseria species that is closely related to Neisseria cinerea. The source of the other region was unclear.     

Solution-state structure by NMR of zinc-substituted rubredoxin from the marine hyperthermophilic archaebacterium Pyrococcus furiosus.

The three-dimensional solution-state structure is reported for the zinc-substituted form of rubredoxin (Rd) from the marine hyperthermophilic archaebacterium Pyrococcus furiosus, an organism that grows optimally at 100 degrees C. Structures were generated with DSPACE by a hybrid distance geometry (DG)-based simulated annealing (SA) approach that employed 403 nuclear Overhauser effect (NOE)-derived interproton distance restraints, including 67 interresidue, 124 sequential (i-j = 1), 75 medium-range (i-j = 2-5), and 137 long-range (i-j > 5) restraints. All lower interproton distance bounds were set at the sum of the van Der Waals radii (1.8 A), and upper bounds of 2.7 A, 3.3 A, and 5.0 A were employed to represent qualitatively observed strong, medium, and weak NOE cross peak intensities, respectively. Twenty-three backbone-backbone, six backbone-sulfur (Cys), two backbone-side chain, and two side chain-side chain hydrogen bond restraints were include for structure refinement, yielding a total of 436 nonbonded restraints, which averages to > 16 restraints per residue. A total of 10 structures generated from random atom positions and 30 structures generated by molecular replacement using the backbone coordinates of Clostridium pasteurianum Rd converged to a common conformation, with the average penalty (= sum of the square of the distance bounds violations; +/- standard deviation) of 0.024 +/- 0.003 A2 and a maximum total penalty of 0.035 A2. Superposition of the backbone atoms (C, C alpha, N) of residues A1-L51 for all 40 structures afforded an average pairwise root mean square (rms) deviation value (+/- SD) of 0.42 +/- 0.07 A. Superposition of all heavy atoms for residues A1-L51, including those of structurally undefined external side chains, afforded an average pairwise rms deviation of 0.72 +/- 0.08 A. Qualitative comparison of back-calculated and experimental two-dimensional NOESY spectra indicate that the DG/SA structures are consistent with the experimental spectra. The global folding of P. furiosus Zn(Rd) is remarkably similar to the folding observed by X-ray crystallography for native Rd from the mesophilic organism C. pasteurianum, with the average rms deviation value for backbone atoms of residues A1-L51 of P. furiosus Zn(Rd) superposed with respect to residues K2-V52 of C. pasteurianum Rd of 0.77 +/- 0.06 A. The conformations of aromatic residues that compose the hydrophobic cores of the two proteins are also similar. However, P. furiosus Rd contains several unique structural elements, including at least four additional hydrogen bonds and three potential electrostatic interactions.(ABSTRACT TRUNCATED AT 400 WORDS)     

利用普通怯寄蝇防治菜粉蝶初探

1 前言 从外地引进寄蝇或人工助长当地寄蝇种类防治农林害虫,是有效的生防手段之一,国外已有很多成功的报道。King等(1981)在路易斯安娜州蔗田中人工大量释放螟利索寄蝇(Lixophaga diatraeae)成虫防治第1代小蔗杆草螟(Diatraea saccharalis),不同地区的寄生率分别达到4.1、8.7和35.7％;由于降低了农药的使用量,奇痣窄径茧蜂(Agathis stigmatera)的自然寄生率也相应提高,很好地控制了蔗田害虫的发生。在寄蝇的田间释放技术方面,国外还没有详细的报道。在我国,利用寄蝇防治害虫的工作也是刚刚起步,很多具体问题有待于进一步研究。     

A dye release assay for determination of lysostaphin activity

We describe a method for determination of lysostaphin activity using Remazol Brilliant Blue R (RBB)-dyed staphylococcal cells or RBB-dyed staphylococcal peptidoglycan as substrate. The dyed substrates are easy to prepare and are stable for at least 6 months. Soluble hydrolytic products released by lysostaphin are measured spectrophotometrically at 595 nm after the insoluble substrate is removed by filtration or centrifugation. The dye release assay is more sensitive and more accurate than the previously described turbidimetric assay.     

Deoxyribose ring conformation of [d(GGTATACC)]2: an analysis of vicinal proton-proton coupling constants from two-dimensional proton nuclear magnetic resonance

Exchangeable and nonexchangeable protons of [d(GGTATACC)]2 in aqueous cacodylate solution were assigned from two-dimensional nuclear Overhausser effect (2D NOE) spectra. With phase-sensitive COSY and double quantum filtered COSY (DQF-COSY) experiments, the cross-peaks resulting from deoxyribose ring conformation sensitive proton-proton vicinal couplings, i.e., all 1'-2', 1'-2", 2'-3', and 3'-4' couplings and six from 2"-3' couplings, were observed. From the cross-peak fine structure, the 2',2" proton assignments can be confirmed; coupling constants J1'2' and J1'2" and sums of coupling constants involving H2' and H2" for all residues and H3' for C8 were obtained. The DISCO procedure [Kessler, H., Muller, A., & Oschkinat, H. (1985) Magn. Reson. Chem. 23, 844-852] was used to extract individual 1'-2' and 1'-2" coupling constants. The sum of coupling constants involving H1' or H3' was measured from the one-dimensional spectrum where signal overlap is not a problem. Analysis of the resulting coupling constants and sums of coupling constants, in the manner of Rinkel and Altona [Rinkel, L. J., & Altona, C. (1987) J. Biomol. Struct. Dyn. 4, 621-649], led to the following conclusion: C2'-endo deoxyribose ring conformation is predominant for every residue, but a significant amount of C3'-endo conformation may exist, ranging from 14% to 30%.     

Comparison of activity and conformation changes during refolding of urea-denatured creatine kinase

The course of the recovery of the enzymatic activity and the native conformation during the renaturation of urea-denatured creatine kinase (ATP:creatine N-phosphotransferase, EC 2.7.3.2) has been studied. Under suitable conditions, an activity recovery of 95% can be obtained and the reactivation follows a triphasic course. The initial two phases are relatively fast, whereas the slow phase takes some 24 h to reach completion. The recovery of the native conformation has been followed by changes in fluorescence, ultraviolet absorption and in exposed SH groups and has been shown to be a biphasic process. Both the reactivation and the refolding processes are independent of protein concentrations within a certain range, showing that the dimerization of the enzyme molecule is not rate-limiting. A comparison of the rate constants for the refolding of the molecule with those for the recovery of its catalytic activity shows that these are not synchronized and the activity recovery approaches completion after the refolding and dimerization of the subunits so far as can be detected by the methods employed. The final stage of refolding with complete activity recovery probably involves subtle conformational changes of the dimeric enzyme molecule not detectable by the physiochemical methods used in the present study.     

血友病患者血清中淋巴腺病病毒/人T细胞Ⅲ型病毒抗体检测

对浙江省1982～1984年注射了美国产浓缩Ⅶ因子制剂的18例血友病患者,用酶联免疫吸附法(ELTSA)检测了血清中淋巴腺病病毒/人T细胞Ⅲ型病毒(LAV/HTLV-Ⅲ)抗体,发现4例阳性,并经免疫荧光试验和Western印迹法证实。2例应用了国产浓缩Ⅷ因子者抗体阴性。一例从美国来华旅游死于艾滋病者,LAV/HTLV-Ⅲ抗体阳性。本研究证明,LAV/HTLVⅢ病毒巳通过美国生产的Ⅷ因子制剂传入中国。     

广西德峨苗族、彝族体质调查

对广西隆林县德峨乡男性22至60岁与女性20至60岁的576名苗族人(男395、女181)和178名彝族人(男88、女90)进行了活体观察与测量,计算出各项数据,总结德峨苗族、彝族的体质特征,并与国内一些民族相比较。