小分子免疫调节剂 L—2—(3—羟基—4—羟甲基苯基)—甘氨酸前体物 DL—2—(3—羟基—4—羟甲基苯基)—N—乙酰基甘氨酸的合成

本文通过对小分子免疲调节剂L—2—(3—羟基—4—羟甲基苯基)—甘氨酸(英文名:Forphenicinol)前体物DL—2—(3—羟基—4—羟甲基苯基)—N—乙酰基甘氨酸的合成方法研究,探索了终产物Forphenicinol 的合成路线及实验方法、并通过对各步产物之红外光谱分析,确证各步产物之主要特征吸收峰,为今后的合成工作打下良好之基础、     

DL—1—(2,6—二甲基苯氧基)—2——氨基丙烷氨基酸衍生物的研究

<正> DL—1—(2,6—二甲基苯氧基)—乙—氨基丙烷盐酸盐,商品名为慢心律(Mcxiletine)是七十年代进行临床研究的一个抗心律失常药物。目前国内外广泛用于临床,其特点是可以长期口服治疗和预防室性心律失常。根据国内外近十年的临床观察,若用量超过600—800mg/日,则有明显副作用如神经兴奋、噁心、复视、抽搐、振颤等。为了寻找更理想的抗心律失常药物,国内外已做过一些慢心律的类似物供药理筛选研究。本文是从前体药物的角度以慢心律自由碱DL—1—(2,6—甲基苯氧基)—2—氨基丙     

新型O—连接糖基化—O—GlcNAc

一种新型糖基化,单糖Ｎ－乙酰葡萄糖胺通过Ｏ－连接与蛋白质共价相连,随着研究的不断深入,这种新型糖基化受到愈来愈多的重视,本主要论述它的发现,存在部位及可能的功能。     

非典—SARS—冠状病毒

2002年11月,一种神秘不明的疾病出现在我国广东省继而肆虐全球,世界上有27个国家和地区相继报道出现这种疫情。由于这种疾病的症状不同于典型肺炎,故初期称之为“非典型肺炎”(简称“非典”)并沿用至今。其学名应称为“严重急性呼吸综合征”(Severe Acute Respiratory Syndrome,     

越南——黄连国家公园

说起越南,国人头脑里首先出现的是下龙湾、芽庄、岘港这些海边的旅游胜地,而相比之下西方人则更钟情于越南北部大山里的一个小县——沙坝（Sa Pa）。这个被誉为亚洲的＂欧洲小镇＂＂越南丽江＂的地方不仅有美丽的法式风格建筑和独特的越南少数民族的风情,更著名的名片则是秀色可餐的黄连国家公园。     

水中精灵——热带鱼

一说起热带鱼,很多人脑海中就浮现出色彩斑斓的小鱼欢快游动的情景,但是这情景很可能是朦胧的,因为我们大多数人对于热带鱼都没有很清晰的概念,也可以说,热带鱼本身就没有一个明确的定义。     

嗜碱细菌环状糊精葡糖基转移酶的纯化和性质

嗜碱细菌52—2除去菌体的培养液经硫酸铵沉淀和DEAE－纤维素离子交换柱层析,得到凝胶电泳均一的环状糊精葡糖基转移酶,纯化了11.5倍,酶活力回收为5.7％。用浓度梯度PAGE测分子量为151700。酶反应最适温度为65℃,50℃以下比较稳定。酶反应最适pH为7．0,在6．0～9.0范围内稳定。Zn²⁺、Hg²⁺、Pb²⁺、Al³⁺、Cu²⁺、Ag⁺和Fe²⁺强烈抑制酶活力。紫外光谱在270nm和244nm处分别有最大和最小吸收。荧光光谱的最大激发波长和发射波长分别为283nm和335nm。用NBS、NEM、NAI、DEP和EDC对酶进行了化学修饰,初步推测组氨酸和色氨酸残基可能为酶活力必需基因,羧基与酶活力有一定关系。     

Purification and properties of an extracellular endoglucanase from Myceliophthora thermophila D-14 (ATCC 48104)

An extracellular endoglucanase (1,4-beta-glucanohydrolase, EC 3.2.1.4) produced by Myceliophthora thermophila D-14 (ATCC 48104) has been purified to homogeneity by ammonium sulphate precipitation and two consecutive ion-exchange chromatographic steps on DEAE-Sephadex A-50 columns. The enzyme was purified 13.8-fold and was homogeneous by analytical PAGE and SDS-PAGE. It has a high apparent Mr, of about 100,000. The pH and temperature optima for its activity were 4.8 and 65 degrees C respectively. The Km of the purified enzyme for CMC (sodium salt) was 3 mg ml-1. The enzyme displayed low activity toward salicin and p-nitrophenyl beta-D-glucoside. The activity was enhanced in the presence of Na+, K+ and Ca2+ but effectively inhibited by Hg2+, Fe2+, Mg2+, Cu2+ and NH4+. Inhibition studies indicated that the enzyme may be a metalloprotein and/or that it requires metal ions for its optimum activity.     

Properties of the isoenzyme forms A-1, A-2 and B of N-acetyl-beta-D-glucosaminidase purified from baboon kidneys

Three forms of N-acetyl-beta-D-glucosaminidase (NAG: A, B and I) were separated from baboon kidney using Con A-Sepharose and DEAE-Trisacryl chromatography. 2. The A form was further purified into two forms A-1 and A-2 using hydroxylapatite chromatography and anodic PAGE. Both were homogeneous on SDS-PAGE and anodic PAGE but microheterogeneous on PAG-IEF, which could be eliminated by prior treatment with endoglycosidase H or glycopeptidase F. 3. The carbohydrate content accounted for some of this microheterogeneity since it varied from 31 for A-1 to 17% for A-2 and the sialic acid was 6 and 1%. Deamidation may also contribute since the acidic amino acids (29 mol%) and ammonia were high following acid hydrolysis. 4. The mol. wt for A-1, determined by SDS-PAGE, was 52.1 K. 5. The pH optimum was 4.55 and the pI4.97. 6. The optimum temperature for NAG A and B was 50 degrees and 42 degrees C, but B retained more activity above 55 degrees C. 7. The Km for N-acetyl-beta-D-glucosamine and -galactosamine for both isoforms was 0.497 and 0.627 mM respectively. 8. Several ions were found to be uncompetitive inhibitors. Ag+ and Pb2+ were the most potent having Ki values of 3.6 and 8.5 mM respectively. Acetate acted as a competitive inhibitor.     

Purification and properties of an extracellular pectin lyase produced by the strain of Penicillium oxalicum in solid-state fermentation

A pectin lyase (PNL, EC 4.2.2.10) produced extracellularly by the strain of Penicillium oxalicum in solid-state fermentation medium containing deoiled mandarin orange peel meal was purified to apparent homogeneity by a protocol that included ammonium sulfate precipitation, DEAE-Sephadex A-50 and Sephadex G-100 chromatography. The enzyme had molecular mass of 50 kD, as determined by SDS- PAGE and showed optimum pH and temperature at 8.0 and 50 degrees C respectively. It had an isoelectric point (pI) of 5.0 and showed a K(m) of 1.1 mg/ml of citrus pectin. The enzyme was strongly inhibited by Mo4+, Ag+ and Pb2+ and also by polyphenolic compounds, in particular tannic acid.     

Purification and characterization of a collagenase from the mackerel,Scomber japonicus

Collagenase from the internal organs of a mackerel was purified using acetone precipitation, ion-exchange chromatography on a DEAE-Sephadex A-50, gel filtration chromatography on a Sephadex G-100, ion-exchange chromatography on DEAE-Sephacel, and gel filtration chromatography on a Sephadex G-75 column. The molecular mass of the purified enzyme was estimated to be 14.8 kDa by gel filtration and SDS-PAGE. The purification and yield were 39.5-fold and 0.1% when compared to those in the starting-crude extract. The optimum pH and temperature for the enzyme activity were around pH 7.5 and 55 degrees, respectively. The K(m) and V(max) of the enzyme for collagen Type I were approximately 1.1mM and 2,343 U, respectively. The purified enzyme was strongly inhibited by Hg2+, Zn2+, PMSF, TLCK, and the soybean-trypsin inhibitor.     

Enolase from Candida albicans--purification and characterization

This paper describes isolation of electrophoretically homogenous enolase from Candida albicans. The purification involved: disintegration of C. albicans cells in a Braun's mill (67-100%) ammonium sulfate precipitation, chromatography on DEAE-Sephadex A-50 at pH 9.0 and chromatography on CM-Sephadex A-50 at pH 6.2. The procedure resulted in a 30-fold purification of the enzyme with a recovery rate of 6% and a specific activity 35 U mg-1. The subunit molecular weight was 46 kDa and the pH optimum of the enzyme was 6.8. Km and Vmax values for the 2PGA-->PEP reaction were determined (Km = 0.95 mM, Vmax = 4200 mumol min-1 mumol-1). In the absence of orthophosphate, inhibition by fluoride was competitive, which became noncompetitive in the presence of phosphate. It was confirmed that Mg2+ is the most potent activator (Km = 0.286 mM); Mn2+ gave less activity and Zn2+ less still. It was also demonstrated that the presence of two types of cations in the reaction mixture nullified the activatory effect of the stronger agent. Properties of the enzyme from C. albicans are compared with those of enolases from other sources.     

诺卡氏菌形放线菌β-甘露聚糖酶的纯化和性质

产β－１,４－Ｄ甘露聚糖酶的诺卡氏菌形放线菌（Ｎｏｃａｒｄｉｏｆｏｒｍ ａｃｔｉｎｏｍｙｃｅｔｅｓ）菌株ＮＡ３－５４０,发酵培养７２ｈ,发酵液离心去菌体,上清经硫酸铵沉淀,９５％乙醇沉淀,ＣＭ－Ｓｅｐｈａｄｅｘ Ａ５０柱层析、羟基磷灰石柱层析、ＤＥＡＥ－纤维素离子交换及Ｓｅｐｈａｄｅｘ Ｇ－１００分子凝胶过滤柱等步骤,β－甘露聚糖酶的比活提高了１３７倍,获得凝胶电泳均一的蛋白样品。经ＳＤＳ－ＰＡＧ     

Purification, stability and kinetic properties of highly purified adenosine deaminase from Bacillus cereus NCIB 8122

Adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4) from Bacillus cereus NCIB 8122 has been purified to electrophoretic homogeneity by ammonium sulfate precipitation, gel filtration through Sephadex G-100, DEAE-Sephadex A-50 chromatography and ion-exchange HPLC on DEAE-Polyol. The enzyme activity is stabilized (at temperatures from 0 degrees C to 40 degrees C) by 50 mM NH4+ or K+, while it is irreversibly lost in the absence of these or a few other monovalent cations. Glycerol (24% by volume) helps the cation in stabilizing the enzyme activity above 40 degrees C, but also exerts per se a noticeable protecting effect at room temperature. B. cereus adenosine deaminase displays the following properties: Mr on Sephadex G-200, 68,000; Mr in SDS-polyacrylamide gel electrophoresis, 53,700; optimal pH-stability (in the presence of 50 mM KCl) over the range 8-11 at 4 degrees C, and maximal catalytic activity at 30 degrees C between pH 7 and 10; Km for adenosine around 50 microM over the same pH range and Km for 2'-deoxyadenosine around 400 microM.     

Bovine spleen cathepsin B1 and collagenolytic cathepsin. A comparative study of the properties of the two enzymes in the degradation of native collagen.

Bovine spleen cathepsin B1 and collagenolytic cathepsin were separated by chromatography on Amberlite IRC-50 and collagenolytic cathepsin was partially purified by chromatography on DEAE-Sephadex (A-50). 2. Collagenolytic cathepsin degraded insoluble tendon collagen maximally at pH 3.5 and 28 degrees C; mainly alpha-chain components were released into solution. At 28 degrees C the telopeptides in soluble skin collagen were also cleaved to yield alpha-chain components. Collagenolytic cathepsin was thus similar to cathepsin B1 in its action against native collagen, but mixtures of these two enzymes exhibited a synergistic effect. 3. The addition of thiol-blocking compounds produced similar inhibition of collagenolytic cathepsin and cathepsin B1. The enzyme responded similarly to all other compounds tested except to 6-aminohexanoic acid, when collagenolytic cathepsin was slightly activated and cathepsin B1 was almost unaffected. 4. Leupeptin, which is a structural analogue of arginine-containing synthetic substrates, inhibited collagenolytic cathepsin as effectively as cathepsin B1. Collagenolytic cathepsin was shown to retain a low residual activity against alpha-N-benzoyl-DL-arginine p-nitroanilide during purification which was equivalent to 0.2% of the activity of cathepsin B1. 5. Cathepsin B1 and collagenolytic cathepsin could not be separated by affinity chromatography on organomercurial-Sepharose 4B. The two enzymes could be resolved on DEAE-Sephadex (A-50) and by isoelectric focusing in an Ampholine pH gradient. The pI of the major cathepsin B1 isoenzyme was 4.9 and the pI of collagenolytic cathepsin was 6.4. 6. From chromatography on Sephadex G-75 (superfine grade) the molecular weights were calculated to be 26000 for cathepsin B1 and 20000 for collagenolytic cathepsin. The difference in molecular weight was confirmed by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis.     

Isolation and properties of carboxylesterase from hemolymph of the silkworm Bombyx mori L

An original procedure for isolation and purification of carboxylesterase from the hemolymph of stage V larvae of one of Bombyx mori strains including precipitation with 10% polyethyleneglycol, ion-exchange chromatography on Sephadex G-200 and chromatography on DEAE-Sephadex A-50, has been developed. The specific activity of the enzyme after purification makes up to 1250 units per mg of protein with a 59% yield. Some physicochemical properties of the enzyme (Mr = 69 000, pI congruent to 4.9, temperature optimum = 40 degrees, pH optimum = 7.2 Km for alpha-naphthyl- and beta-naphthylacetate = 0.11 X 10(-3) and 0.52 X 10(-3) M, respectively) have been determined. Using immunodiffusion in agar gel, the antigenic identity of the enzymes isolated from the hemolymph of two silkworm species has been established.