Total chemical synthesis and NMR characterization of the glycopeptide tx5a, a heavily post-translationally modified conotoxin, reveals that the glycan structure is alpha-D-Gal-(1-->3)-alpha-D-GalNAc.

The 13-amino acid glycopeptide tx5a (Gla-Cys-Cys-Gla-Asp-Gly-Trp*-Cys-Cys-Thr*-Ala-Ala-Hyp-OH, where Trp* = 6-bromotryptophan and Thr* = Gal-GalNAc-threonine), isolated from Conus textile, causes hyperactivity and spasticity when injected intracerebral ventricularly into mice. It contains nine post-translationally modified residues: four cysteine residues, two gamma-carboxyglutamic acid residues, and one residue each of 6-bromotryptophan, 4-trans-hydroxyproline and glycosylated threonine. The chemical nature of each of these has been determined with the exception of the glycan linkage pattern on threonine and the stereochemistry of the 6-bromotryptophan residue. Previous investigations have demonstrated that tx5a contains a disaccharide composed of N-acetylgalactosamine (GalNAc) and galactose (Gal), but the interresidue linkage was not characterized. We hypothesized that tx5a contained the T-antigen, beta-D-Gal-(1-->3)-alpha-D-GalNAc, one of the most common O-linked glycan structures, identified previously in another Conus glycopeptide, contalukin-G. We therefore utilized the peracetylated form of this glycan attached to Fmoc-threonine in an attempted synthesis. While the result-ing synthetic peptide (Gla-Cys-Cys-Gla-Asp-Gly-Trp*-Cys-Cys-Thr*-Ala-Ala-Hyp-OH, where Trp* =6-bromotryptophan and Thr* = beta-D-Gal-(1-->3)-alpha-D-GalNAc-threonine) and the native peptide had almost identical mass spectra, a comparison of their RP-HPLC chromatograms suggested that the two forms were not identical. Two-dimensional 1H homonuclear and 13C-1H heteronuclear NMR spectroscopy of native tx5a isolated from Conus textile was then used to determine that the glycan present on tx5a indeed is not the aforementioned T-antigen, but rather alpha-D-Gal-(1-->3)-alpha-D-GalNAc.     

尿素氮-葡萄糖双功能分析仪的研究

由固定化脲酶、谷氨酸脱氢酶、谷氨酸氧化酶、葡萄糖氧化酶的复合酶膜组成的双电极系统,可以同时测定尿素氮和葡萄糖的含量,每次进样量为25μl,20s即可测定出尿素氮和葡萄糖的含量。在0～60mg/dl尿素氮、0～500mg/dl葡萄糖范围内具有良好的线性关系。连续测定20次的变异系数分别为1.02％和1.05％。酶膜使用寿命为两星期以上。此仪器可广泛应用于临床检验和体育训练中。     

Morphometric Analysis of Hepatocellular carcinoma

Ｍｏｒｐｈｏｍｅｔｒｉｃ　Ａｎａｌｙｓｉｓ　ｏｆ　Ｈｅｐａｔｏｃｅｌｌｕｌａｒ　ｃａｒｃｉｎｏｍａＬａｉＭａｏ－ｄｅ（来茂德）;ＣｈｅｎＰｅｉ－ｈｕｉ（陈培辉）ａｎｄＺｈｏｕＳｈｕｉ－ｙｕｎ（周水云）（ＤｅｐａｒｔｍｅｎｔｏｆＰａｔｈｏｌｏｇｙ,Ｚｈ...     

木瓜蛋白酶PPAⅢ自水解作用

木瓜蛋白酶ＰＰＡⅢ自水解作用王秀艳,周慧,葛玉斌,李惟（吉林大学分子生物学系,长春１３００２３）ＰＰＡⅢ、ｐａｐａｉｎ、ｐｅｐｓｉｎｅ、ｓｔｅｍｂｒｏｍｅｌａｉｎ等都属于以Ｃｙｓ－ＳＨ为活性中心的酶,同种分子之间存在着一种相互切割的趋势,称为酶自水解...     

黄精凝集素Ⅱ分子稳定性与生物学活性研究

黄精凝集素Ⅱ分子稳定性与生物学活性研究鲍锦库,曾仲奎,周红（四川大学生物系,成都,６１００６４）本文在黄精凝集素Ⅱ纯化及性质研究的基础上,应用多种变性条件,研究其分子特性,同时对分子的巯基和色氨酸进行修饰,研究该凝集素分子保持其生物学活性与这些基团的...     

POPULATION SEASONALITY AND LARVAL DEVELOPMENT OF LAGRIA HIRTA L. (COLEOPTERA: LAGRIIDAE)*

Abstract The seasonality of the field population of Lagria hirta L. is remarkable: adults occur only from the end of June to the beginning of August, whereas larvae exist in the whole year except June. Based on the data of field observations and larval head-width measuring, the author demonstrated that L. hirta would reproduce in a very short interval in June to August; eggs hatch and develop (molt) into the 3rd, 4th or 5th (sometimes 6th) instar before winter; after larval overwintering, the beetles complete the larval development after total 8–10 times of molts and pupate in June. The larval development rate is decreased but not completely stopped during winter (the nonparametric median test, P<0. 01). This result changes the hitherto opinion of 4 or 5-instar larval development of L. hirta and will stimulate the studies on its life history.     

Identification of a 175 kDa protein as the ligand-binding subunit of the rat liver sinusoidal endothelial cell hyaluronan receptor

The rat liver sinusoidal endothelial cell (LEC) hyaluronan (HA)receptor was previously identified using a photoaffinity HAderivative (J. BioL Chem., 267, 20451–20456, 1992). Twopolypeptides with M_r = 175,000 and 166,000, were consistentlycrosslinked, suggesting that the LEC HA receptor is an oligomer.Whether one or both subunits participate in HA binding, wasnot determined. Here we investigate the HA-subunit interactionsand the potential oligomeric nature of the LEC HA receptor.When Sephacryl-400 gel filtration chromatography was used toenrich the HA receptor, the 175 kDa polypeptide was the majorband seen by SDS-PAGE analysis. Little staining was seen at166 kDa, suggesting that the 175 kDa protein could be separatedfrom the 166 kDa protein and still retain HA-binding activity.A ligand blot assay was used to determine if each individualsubunit could bind HA. LEC proteins were separated by nonreducingSDS-PAGE, and then immobilized onto nitrocellulose. ¹²⁵I-HAbound to a 175 kDa polypeptide but not to the 166 kDa protein.A high molecular weight band of     

Polyamine derivatives as inhibitors of trypanothione reductase and assessment of their trypanocidal activities

Trypanothione reductase (TR) occurs exclusively in trypanosomes and leishmania, which are the etiological agents of many diseases. TR plays a vital role in the antioxidant defenses of these parasites and inhibitors of TR have potential as antitrypanosomal agents. We describe the syntheses of several spermine and spermidine derivatives and the inhibiting effects of these compounds on T. cruzi TR. All of the inhibiting compounds displayed competitive inhibition of TR-mediated reduction of trypanothione disulfide. The three most effective compounds studied were N⁴,N⁸-bis(3-phenylpropyl)spermine (12), N⁴,N⁸-bis(2-naphthylmethyl)spermine (14), and N¹,N⁸-bis(2-naphthylmethyl)spermidine (21), with K_i values of 3.5, 5.5 and 9.5 μM, respectively. Compounds 12, 14, and 21 were found to be potent trypanocides in vitro with IC₅₀ values ranging from 0.19 to 0.83 μM against four T. brucei ssp. strains. However, these compounds did not prolong the lives of mice infected with trypanosomes. This work indicates that certain polyamine derivatives which target a unique pathway in Trypanosomatidae have potential as antitrypanosomal agents.