Résumé
A beta-amylase gene (amyG) was cloned from a Bacillus megaterium WS06 and expressed in the Escherichia coli. Nucleotide sequence anlysis showed the amyG gene is composed of 1638 bp (545 amino acid residues with a Mr of 60.194 kD). The AmyG shows 94.5% sequence homologies with beta-amylase from Bacillus megaterium DSM319 and presents a normal beta-amylase primary structure, constituted by three parts: the N-terminal signal sequence, the catalytic domain and the C-terminal starch binding domains. The deduced amino acid sequence revealed that several highly conserved regions of the glycosylhydrolase family 14. The amyG gene was overexpressed using the pET21a vector and Escherichia coli BL21(DE3). The recombinant enzyme was purified 7.4 fold to electrophoretic homogeneity and had a Mr of 57 kD (by SDS-PAGE). The enzyme was optimally active at pH 7.0 and 60 degrees C and showed stability at the temperature below 60 degrees C. This enzyme efficiently hydrolyzed starch to yield maltose from non-reducing chain ends by exo-cleavage mode.
Sujets)
Bacillus megaterium , Génétique , Clonage moléculaire , Escherichia coli , Génétique , Métabolisme , Vecteurs génétiques , Génétique , Protéines recombinantes , Génétique , Métabolisme , Analyse de séquence de protéine , Similitude de séquences d'acides aminés , Température , beta-Amylase , Génétique , MétabolismeRésumé
【Objective】To explore the effect of acupoint catgut implantation(ACI) on hypothalamic monoamine neurotransmitters in rats treated with clozapine.【Methods】Thirty-six SD rats were randomized into ACI group,clozapine group and blank control group.Except the blank control group,the rats in other two groups received clozapine.The dosage of clozapine for the rats was 5 mg?kg-1?d-1 at the first time,increased to 30 mg?kg-1?d-1,and then reduced to 22 mg?kg-1?d-1 which maintained till the end of the experiment.After 60-day treatment with clozapine,ACI group was treated with ACI alternatively on Baihui(GV20),bilateral Xinshu(BL15) and bilateral Quchi(LI11),or on Dazhui(GV14),bilateral Pishu(BL20),bilateral Zusanli(ST36),one time every 5 days,12 times in total.The changes of body weight before and after treatment,and the hypothalamic monoamine neurotransmitters contents of dopamine(DA) and 5-hydroxytryptamine(5-HT) were observed in the three groups.【Results】In the clozapine group,the rats body weight markedly increased,and the contents of DA and 5-HT decreased(P
Résumé
Purified GAI, one form of glucoamylase obtained from Aspergillus niger mutant T21 contained 17.6% total carbohydrate. Analyses of amino acid composition showed that GAI contained about 25% Ser and Thr, 20.3% Asx and Glx and 6% basic amino acids. The UV absorption and fluorescence spectra of GAI were determined. The maximum absorption wavelength was at 278nm and minimum at 250nm. For fluorescent analyses the excitation and maximum emission spectra were at 284nm and 342nm respectively. The CD-spectrum determined showed two negative peaks. Its dispersion of secondary structure in solution showed 10.6% ?-helix, 16.3% ?-form and 73.1% unordered.