Kinetic Study on Cephamycin C Degradation

Cephamycin C (CepC) is a β-lactam antibiotic that belongs to the cephalosporin class of drugs. This compound stands out from other cephalosporins for its greater resistance to β-lactamases, which are enzymes produced by pathogenic microorganisms that present a major mechanism of bacterial resistance to β-lactam antibiotics. Cephamycin C is produced by the bacterium Streptomyces clavuligerus. Knowledge about the stability of the compound under different values of pH is important for the development of the process of production, extraction, and purification aimed at obtaining higher yields. Therefore, the stability of cephamycin C under different pH levels (2.2, 6.0, 7.0, 7.6, and 8.7) at 20 °C was evaluated in this study. Ultrafiltered broth from batch fermentations of S. clavuligerus was used in the trials. The results indicated that cephamycin C is a more stable compound than other β-lactam compounds such as penicillin and clavulanic acid. A higher degradation rate was observed at very acidic or basic pH levels, while this rate was lower at quasi-neutral pH levels. After 100 h of trial, the initial CepC showed 46 % degradation at pH 2.2, 71 % degradation at pH 8.7, and varied from 15 to 20 % at quasi-neutral pH levels.     

Studies of Cephalosporin C Purification by Ultrafitration

Cephalosporin C was produced with fermentation technique. There are many impurities (mycelium, protein et al) in its fermentation liquor, which can be removed by ultrafitration membrane separation. The ultrafiltration technique has been used for purifying the fermentation liquid of antibiotics^[1-2],however, its application in extraction of Cephalosporin C from its fermentation liquor has not been reported. In this paper, we use Ultra-flo ultraflitration membrane system (concludes UF-54 pilot plant, flat board membrane module, thin composite membrane of 30 thousand reject molecular weight) to purify #1-#3 fermentation liquors of Cephalosporin C, which were not pretreated except acidification(pH=3).     

液相组合合成的纯化方法

综述了近8年来液相平行合成和组合合成中应用的不同技术, 包括可溶性载体、氟合成技术、离子液体、固相试剂树脂以及低聚乙烯二醇(OEG)衍生物的应用等几方面内容. 论述了它们的基本原理以及相关的应用实例, 并着重强调了目标化合物的分离纯化方法.     

纯化基因重组白细胞介素-2的初步研究

 采用羟基磷灰石 (HAP)作为填料 ,以pH 6 8的磷酸盐缓冲液为流动相 ,用制备型高效液相色谱来分离提纯基因重组白细胞介素 2 (IL 2 ) ,通过SDS 聚丙烯酰胺凝胶 (SDS PAGE)电泳测定IL 2的纯度 ,测定其活性为1× 1 0 6 U/mg。该法对IL 2的纯化、含量测定及活性测定等效果良好。     

Preliminary Studies on X-Ray-sensitive Liposome

The synthesis of a new type of X-ray-sensitive compound “di-(1-hydroxylundecyl)diselenide” and its application in the preparation of a new type of liposome with X-ray sensitivity was reported.This new ...     

MALDI-TOF-MS测定溶菌酶的相对分子质量中在线纯化技术的应用

用基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)测定溶菌酶的相对分子质量,采用硝酸纤维素膜作为溶菌酶的固相载体,在质谱仪上进行在线纯化溶菌酶样品,在测试前尽可能除去样品中的添加剂,以消除一些盐和蛋白质变性剂抑制样品峰的情形;此法简单、快速,并可明显增强离子峰的强度,提高测试的灵敏度。     

细胞色素C的光谱研究

细胞色素C是吸呼链的1个重要组成部分,位于细胞色素C₁和细胞色素a之间,血红素辅基中的铁原子可交替地处于+3或+2氧化态^[1]。Smith^[2]和Osheroff等^[3]对细胞色素C与细胞色素C₁及a的结合进行了详细的研究。关于细胞色素C与小分子的相互作用,除Corthesy^[4]进行了与ATP的作用,Osheroff^[3]进行了与碳酸根的作用外,与其它小分子的作用以及氧化型、还原型之间的相互转化受介质的影响还未见报道。     

Purification of rabbit skeletal muscle troponin C

Troponin C binds to phenyl-Sepharose in the presence of Ca2+ and can be eluted with EDTA. This property was used as an essential step in the purification of this protein from rabbit skeletal muscle. Troponin C was extracted with 6M urea from extensively washed ground muscle. The protein was bound to and eluted from DEAE-Sephadex, fractionated by size on Sephadex G75, and in a final step purified from UV-absorbing non-protein impurities on phenyl-Sepharose. The total yield of electrophoretically pure protein was 60 mg per 100 g of muscle, which is considerably higher than that previously obtained.     

Preliminary Studies of a Bacterial Sulfate Electrode

Abstract

A bacterial electrode for sulfate was developed by coupling a strain of the bacterium Desulfovibrio desulfuricans with a sulfide selective electrode. This bacterium reduces sulfate to sulfide by a complex multistep enzymatic reaction sequence. The response of this sensor to sulfate is Nernstian in the concentration range of 4 × 10^?5 to 7 × 10^?4 M. The electrode functions for a period up to 10 days when stored in growth medium under a nitrogen atmosphere. However, it is necessary to keep the sensor in an oxygen-free environment at all times, because oxygen irreversibly inhibits the required enzymes. Although this limits the practical utility of this sensor, alternative configurations for a more practical analytical system are proposed.     

HC-SCR技术应用于稀薄燃烧条件下NOx净化研究进展

介绍了稀薄燃烧发动机尾气排放特点,并对稀薄燃烧条件下NO2的净化技术(尤其是HC-SCR技术)加以综述,最后提出建议和设想。     

Purification of isoenzyme I of phospholipase C from Clostridium perfringens

V. I. Lenin Tashkent State University. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 888–890, November–December, 1988.     

Purification of phospholipase C by hydrophobic interaction affinity chromatography.

A simple procedure is described for the purification of phosphatidylcholine-hydrolyzing phospholipase C(PLC). Lecithin, the substrate for PLC, was ligated hydrophobically to octyl-Sepharose in 2 M (NH4)2SO4. The washed lecithin-conjugated resin was then used to purify PLC from crude preparations by affinity chromatography. PLC binds to the lecithin moiety in the presence of Zn2+ and is eluted with an acidic buffer containing EDTA. PLC activity was recovered in the eluate. Both sodium dodecyl sulphate polyacrylamide gel electrophoresis and pI electrofocusing showed that the eluate contained a single monomeric protein with an apparent molecular mass of 66 kDa and a pI of 5.5.     

医学成像光谱技术研究进展

从成像光谱技术的发展概况出发,综述了医学成像光谱技术的研究现状和最新进展,对现有的医学成像光谱仪按照类别进行分析,对其在生物医学领域应用概况和应用前景进行了探讨.对医学成像光谱技术的发展趋势和今后研究需要解决的问题进行了评述.     

Use of a Dynamic Light Scattering Technique for SDS/Water/Pentanol Studies

The interpretation of micelle/aggregate size obtained by use of the DLS technique for SDS/water/pentanol systems was discussed by comparison of the results of measurement with theoretical data. For most of the studied systems, the apparent radii (R _h,app ) did not satisfactorily characterize the size of the aggregates (R _h,app  < 1 nm). The use of a correction factor (f = 0.26) confirmed that the discrepancies were associated with the electrostatic intermicellar interactions. However, the fuzzy optical interface between dispersed and dispersing phases can also be the reason of such results. An increase of pentanol content caused a decrease of the droplet radius in w/o systems but in o/w systems the changes were negligible.     

17400鲨鱼软骨血管生成抑制因子的纯化及生物学活性研究

采用盐酸胍抽提、膜超滤、丙酮分级沉淀、Sephadex-75柱层析和C₄反相高效液相色谱等分离步骤,从广东阳江鲨鱼软骨中纯化获得新的鲨鱼软骨血管生成抑制因子SCAI-c(SharkCartilageAngiogenesis In-hibitor-c,SCAI-c);SDS-PAGE电泳银染显示为一条带,根据蛋白质的相对迁移率计算,分子量为17400;它对鸡胚绒毛尿囊膜血管的形成具有显著抑制效应,并有明显的浓度依赖关系.SCAI-c与SCAI-a具有类似的生物学特征.     

Studies of equilibrium geometries and electronic spectra for C78O4

Equilibrium geometries and relative stabilities of 24 possible isomers for C₇₈O₄ based on C₇₈ (C_2v) were studied by intermediate neglect of differential overlap (INDO) calculations. It was indicated that the most stable geometry is 28,29,30,31,52,53,73,78‐C₇₈O₄, where three oxygen atoms are added to the same hexagon, through which the longest axis of C₇₈ (C_2v) goes, and the forth oxygen atom is added to the C(73)? C(78) bond intersected by the shortest axis of C₇₈ (C_2v), and epoxide structures are formed. Electronic spectra of C₇₈O₄ isomers were investigated based on the optimized geometries. The blue shift of the first absorption for 28,29,30,31,52,53,73,78‐C₇₈O₄ compared with that of C₇₈ (C_2v) was rationalized and nature of transition for the peaks discussed. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006