Abstract:A protein with long polypeptide chain always folds into more than one distinct, compact globular regions that have been designated as domains. Being one of the structural hierarchy, domain is a structural level situating in between secondary and tertiary structure. It is a basic unit to compose three-dimensional structure of protein, to execute the biological function as well as to fold a functional protein. As structural modules, domains may have advantage to compose complex proteins during the process of protein evolution by insertion, deletion and excising. Studies on the structure and interaction of domains can throw light on the study of the relationship between protein structure and function and the design of novel proteins.

Abstract:Direct gene transfer for the treatment of human diseases requires a vector which can be administered efficiently, safely and repeatedly. Cationic liposomes represent one of the few examples that can meet these requirements. Currently, there are more than a dozen cationic liposome formulations. These liposomes bind and condense DNA spontaneously to form complexes with high affinity to cell membranes. Endocytosis of the complexes followed by disruption of the endosomal membrane appears to be the major mechanism of gene delivery. The effectiveness and safety of this DNA delivery method has been established in many studies. Two human gene therapy clinical trials using cationic liposomes have been conducted and more trials will be started in the near future. In the field of gene therapy, cationic liposome is struggling to meet expectations.

Abstract:Based on primary structure comparisons of their carbohydrate-recognition domains(CRDs), the superfamily of mammalian C-type lectins can be divided into six main families: proteoglycans, type Ⅱ transmembrane receptors, collectins, selectins, natural killer cell receptors and multi-CRD type Ⅰ transmembrane receptors, while all members of each family have homologous amino acid sequences, same overall molecular architecture and similar biological functions. The molecular basis for selective carbohydrate recognition by mammalian C-type lectins has been established at the primary to tertiary structure level of CRDs.

Abstract:A new class of introns that possess AT and AC respectively at their 5＇ and 3＇ ends, has been identified in eukaryotic genome. The AT-AC introns differ from the major class of pre-mRNA introns both in structural features and in splicing mechanism. The distribution, structural features and splicing mechanism of AT-AC introns are discussed and compared with major class of introns.

Abstract:During development of central nervous system(CNS) of vertebrate, immature neurons migrate from the place of their proliferative zone to the final destination to exert their function. The neuronal migration with precise temporal and spatial pattern has been viewed as a discrete step in CNS development. Recent studies have shown that this process involves cooperation of a series of molecular events, including interactions of cell adhesive molecules, activation of ion channels, and organization of cytoskeloton. Therefore, it is important not only in elucidating the mechanism of neuronal migration, but also in gaining a new insight into the pathogenesis of brain disorders caused by defective neuronal migration to understand these events.

Abstract:The technique of thermotherapy of tumors has been widely adopted in clinical treatments. But the efficiency is not so ideal in treating the tumor tissues growing in the depth of the body, because of the difficulties in transmission and concentration of heat energy.And another problem to be resolved in tumor thermotherapy is to measure the temperature of tumor tissues being treated with thermotherapy exactly and rapidly. The difficulties in thermo-dosage control affect the efficiency directly. The purpose of temperature autocontrol and stabilization in the thermotherapy of tumors can be achieved through Mn-Zn ferrite, a powdered magnetic absorber which absorbs electromagnetic wave and has Curic temperature. The efficiency can be improved by injecting Mn-Zn ferrite powder into blood vessesls in the course of thermotherapy.

Abstract:The cyclopentenone prostaglandin A2 (PGA2) exhibits potent antiproliferative and antitumor activities both in vitro and in vivo, leading to cell cycle arrest associated with a dramatic decrease in the levels of cyclins and cyclin-dependent kinases(CDKs), and accompanied by an obvious increase of the expression of one of the cdk inhibitors, p21waf1/cip1. p21 waf1/cip1 protein(p21) can also mediate p53 dependent or p53-independent G1 arrest of many cell types, and plays an important role in PGA2-induced cell cycle arrest. Latest progress on the role of interaction of p21 and transcription factor E2F played in PGA2-mediated cell cycle arrest is reviewed.

Abstract:Study of the nucleic acid biosensors have important significance in the fields related to molecular biology. In order to meet the needs for practice, the study of the nucleic acid biosensors was stressed in the sensor field recently. The principles, classification, current status and prospects of the nucleic acid biosensors were described.

Abstract:Reactive oxygen species (ROS) cause various types of damage to many biomolecules, including lipids, proteins, DNA and so on. ROS may contribute to various diseases. Much of the damage caused by superoxide anion radical and hydrogen peroxide in vivo is thought to be due to their conversion into more reactive species, including hydroxyl radical, and probable ferryl iron species. The experimental material and theoretic result have shown that in addition to generation of hydroxyl radical, the ferryl iron species have been proposed to be involved when iron salts are mixed with hydrogen peroxide. The reactive intermediate of Fenton reagents is a nucleophilic adduct. The products profiles and reactivity for Fenton reagents are different from those for free hydroxyl radical and depend upon the transition metal, the ligand, the solvent matrix and substrate.

Abstract:β-1,4-galactosyltransferase (GalTase) can be divided into short and long forms by its mRNA. The short form GalTase within the trans-Golgi compartment participates in the biosynthesis of glycoconjugates. The long form on cell surface mediates cell-cell and cell-matrix interactions by binding to appropriate glycoside substrates on adjacent cell surfaces or in the extracellular matrix, including spermatogenesis, sperm-egg binding, early embryo cell adhesion, secondary trophoblast giant cell migration and neurite outgrowth, and functions as a signal-transducing receptor for extracellular oligosaccharide ligands to affect G protein signal cascades. Surface GalTase also delivers a growth inhibitory signal by modulating the ability of the EGF receptor to transduce EGF-dependent signals, and plays an important role during cell growth.

Abstract:β-Agkistrodotoxin (β₁-AgTx), a presynaptic neurotoxin obtained from the venom of snake Agkistrodon blomhoffii brevicaudus (Jiangshu and Zhejiang Province, China) was further purified by the method of preparative electrophoresis. The polymerism was found in the native component of β₁-AgTx and the purified β₁-AgTx-OH^- which was solubilized in the slight basic solution (pH 7.5) by SDS-PAGE analysis, however, the amount of polymers seems to be stable observed in the different days. Moreover, by two-dimensional electrophoresis analysis, it was found that both components of β₁-AgTx and β₁-AgTx-OH^- were composed of three isoforms (pI 7.0, 5.8 and 5.4) with different contents, and the rate of content of isoforms in the component of β₁-AgTx-OH^- was changeable observed in the different days, but not in the β₁-AgTx.

Abstract:Chicken muscle adenylate kinase was overproduced in soluble form under the transcriptional control of the bacterial phage lambda P_RP_L promoters regulated by temperature sensitive repressors. SDS-PAGE analysis demon-strated that the enzyme was produced to the extent of as much as 38% of the total cellular protein. The soluble recombinant enzyme can be released from bacterial cells and enriched to purity of more than 85% by the Johnson's freeze/thaw method. Mouse anti-rabbit muscle adenylate kinase monoclonal antibody can strongly crossreact with the recombinant enzyme.

Abstract:Human colorectal, pulmonary carcinoma as well as neuroblastoma have been shown to be rich in opiate receptors. A possible targeted fusion protein,consisting of Enkephalin and αⅠ interferon, was constructed, bacterially expressed, and purified. When injected intracerebrally into mice, enkephalin-αⅠ interferon fusion protein caused more potent analgesia than αⅠ interferon. The analgesia effects of the fusion protein were prevented and reversible by opiate antagonist, naloxone and naltridole. The fusion protein also inhibits bindings of ［³H］ DPDPE to opiate receptor. The enkephalin-αⅠ interferon fusion protein was shown to have more antiproliferative and antitumor activities against opiate receptor-bearing tumors, both in vivo and in vitro.These results suggest enkephalin-αⅠ interferon fusion protein may be able to target opiate receptors on tumor cells.

Abstract:The GI mutant, GIK253RA198C, was obtained by in vitro site-directed mutagenesis using the double primer method and then expressed in E.coli K38. The characteristic analysis of the enzymes showed that thermostability of GIK253RA198C was significantly lower as compared with wild-type GI in 80℃. Moreover, its optimum reaction temperature decreased from 75℃ to 70℃. The results are explained by the kinetic parameters. Previous experiment indicated that the same mutation of K253R produced different effects on the thermostablity of SM33 GI and A.missouriensis GI. It is clarified here, based on structure and mechanism, that the result was due to the minor difference between Lys253's positions in the two GI structures.

Abstract:Promotive effect of superoxide and inhibitory effect of EBSELEN on ［3H］DL-glutamate binding to rat cortical synaptosomal membranes were studied by radiolabeled receptor assay. O -·2 results in a marked increase of specific glutamate binding. EBSELEN (1 μmol/L ) shows an inhibition effect on glutamate binding influenced by O -·2.

Abstract:Six phenotypes TfC1, TfC2, TfC1C2, TfC1C3, TfC1Dchi and TfC2Dchi were detected by isoelectric focusing with immobilized pH gradients in pH 5.05～5.60. Tf^C3 has never been revealed in the Han population before. The Gene frequencies are as follows: Tf^C1=0.7420, Tf^C2=0.2420, Tf^C3=0.0027, Tf^Dchi=0.0133. There is a good agreement between the observed and expected values corresponding to the Hardy-Weinberg equilibrium. The allele frequencies for Tf^C1, Tf^C2 and Tf^Dchi are quite similar to those previously reported.

Abstract:By means of proteolysis with trypsin and subtilisin,in the cell wall of Candida utilis, a major structural cell wall protein with molecular mass of 33 ku was found.The 33 ku protein was quite different from most of the other cell wall proteins in Candida utilis. In cell wall it was not hydrolysed by trypsin, but was sensitive to subtilisin. The 33 ku protein was found to exist in cell wall of all logarithmic growth phases. Especially in early logarithmic growth phase, it was proved to be the only protein that was not sensitive to trypsin. The result demonstrated that this protein was important for connection of cell wall skeleton components-glucan, and for the intact structure of cell wall. It was an important integral cell wall protein.

Abstract:Recombinant eukaryotic expression vector DNA containing β-galactosidase gene was injected directly into retina of normal and nerve transected frog Rana pipiens. β-Galactosidase in retina neurons was still identified in two weeks after transfection. Gene transfection to retina neurons is non-selectivity for any neuron. The transfected neurons are around the injection area. Comparing with the normal, the neurons transfected in retina of frog optic nerve transected distribute in a slightly wider area.

Abstract:The primary detection of the MLC₂-chymase fusion gene transgenic mice was carried out by means of polymerase chain reaction(PCR) with two specific primers, which span across MLC2 promoter region and chymase structure gene region. The DNA electrophoretic bands of PCR products were recovered and purified, then sequenced by PCR sequencing method with one of the two primers. Final determination of the transgenic mice was conducted through comparing the sequencing results with sequences of transfered gene. This method is convenient, effective and specific.

Abstract:A method improved for the assay of glycogen synthase(GS) is proposed in the present study. GS activity in NIDDM rat liver is determined by the solid phase filter paper method in comparison with washing method reported in the literatures. There is no obvious difference in the determination of radiation counts between the two methods. This method has been employed in the determination of GS activity of the diabetic rat liver, which exhibited more decrease then the normal rat liver. Therefore, the solid phase filter paper method is simple, convenient for the assay of GS activity and shows no tendency to be polluted.

Abstract:An E.coli strain which could express domain Ⅲ of the extracellular region of the human EGF-R(EGF-RⅢ) in its membrane had been obtained. The results of EGF receptor radiobinding assay showed that ¹²⁵I-EGF could bind specifically to the intact bacterial body, the amount of specific binding varied with the time and temperature of the reaction. The data of Scatchard analysis indicated that the number of the human EGF-RⅢ expressed in the bacteria was about 738 sites/cell, and its dissociation constant was about 3.0×10^-11 mol/L. The sites of the bacteria to which EGF bound were discovered mainly on its membrane by immunoelectronmicroscopy.

Abstract:A λ ZAP expression library of E.coli genomic DNA has been constructed. Screening the library with the Era protein probe labeled by digoxigenin, a plaque specially bound with Era has been isolated from 4×10⁴ plaques. It is confirmed that an Era-binding protein gene exists in E.coli genomic DNA. Compared with the data in GenBank, the 5′ end 800 bp of inserted DNA is located in the section 267 of E.coli genomic DNA.

Abstract:In order to explore effects of senium on metabolism of active oxygen radicals in liver and kidney of rats with fluorosis,2 groups of Wistar rats were fed with normal fodder and high concentration of NaF water (1.58, 2.63 mmol/L fluorine,F).2 groups were fed with selenite fodder (2.0 mg/kg selenium,Se) and high F. At the same time,2 groups were fed with normal fodder and high F for 7 months,then 2.0 mg/kg Se were supplemented in fodder.The contents of free radicals (FR) in liver and kidney were demonstrated by means of the technique of electronic spin resonance (ESR),the contents of Se and F,the activities of glutathion peroxidase (GSH-Px), superoxide dismutase (SOD) and the contents of lipid peroxidase (LPO)in liver and kidney were tested in 14 months.The results showed that there was an increase of F,FR and LPO and a decrease of GSH-Px and SOD in rats with fluorosis. When Se was given in the different time of fluorosis, F lowered, the signal of FR weekened,LPO lessened,GSH-Px and SOD recovered.It indicated that Se not noly could antagonize high F but could rectify metabolic disorders of FR in rats with fluorosis.

Abstract:Streptavidin (6.25 μg/ml, sigma)diluted in distilled water was coated for 3 h (100 μl/well) at room temperature to microtiter strips. Anti-digoxin antibody was modified by biotin. The assay with these strips was used for the measurement of digoxin. It provideds a sensitivity of 0.0964μg/L. The assay has an intra-assay coefficient of variation of 8.9% (at 0.5012 μg/L), 5.9% (at 1.5631 μg/L), 2.4% (at 3.9678 μg/L). The inter-assay coefficient of variation is 15.8% (at 0.8722 μg/L), 10.1% (at 1.1867 μg/L), 9.2% (at 3.1726 μg/L). In spiking experiments with serum samples, the mean recovery of added digoxin is 97.45% (range 89.07%～107.22%). The assay was compared with FPIA. A linear regression analysis yielded a slope of 0.9640, an intercept of 0.1564 and a correlation coefficient of 0.9488.