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Articles by Yu Guo-Yu
Total Records ( 4 ) for Yu Guo-Yu
  Chen Xin-xin , Yu guo-yu , ZHAN Yan , Zhang Yun , Shen Ji-hong and Lee Wen-hui
 

OH-CATH is a novel cathelicidin identified from king cobra. It showed strong antibacterial activity against various bacteria in the presence of 1% NaCl and no haemolytic activity toward human red blood cells even at a high concentration. OH-CATH might serve as model molecules for the development of antimicrobial drugs. Understanding the action mechanism of OH-CATH and the reason for its selectivity against microbes is very important for this purpose. The bactericidal effect of the king cobra antimicrobial peptide OH-CATH on Gram-negative Escherichia coli (ATCC 25922) is observed by scanning electron microscopy (SEM) and transmitted electron microscopy (TEM). The SEM and TEM results suggested that the bactericidal mechanism of OH-CATH against Escherichia coli happened in three steps. Firstly, OH-CATH attached to the negatively charged bacterial wall by positively charged amino acid residues. In the second step, the accumulated OH-CATH aggregated and damaged the bacteria membrane in a pore-forming manner. In the last step, with the damage of cell permeability, the contents of the cells were released and eventually cells died.

  GAO Zhen-hua , ZHAO Hui , YU Guo-yu , ZHANG Yun , SHEN Ji-hong and LEE Wen-hui
 

SgI-29 is a newly characterized antibacterial peptide derived from human semenogelin I. Using SgI-29 as model, 4 peptides with different length were synthesized. Physico-chemical characteristics and structure prediction of SgI-29 and its derived peptides were analyzed by software packages and helix-wheel plot. The antibacterial activities of SgI-29 and its derived peptides against Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 were determined. The structure-function relationship of SgI-29 and its derivatives was analyzed. Our results indicated that SgI-22 has the strongest antibacterial activities against the tested bacteria among the synthetic peptides and might be used as a good model for the structure optimization.

  Yu guo-yu , ZHANG Yong , JIANG Ping , Lee Wen-Hui and Zhang Yun
  Bm-TFF2, an amphibian trefoil factor, which is isolated from skin secretions of frog Bombina maxima, has much stronger biological activities than human TFFs. In the present study, Bm-TFF2 gene was amplified by polymerase chain reaction (PCR) from its cDNA and cloned into Pichia pastoris expression vector pPIC9K containing AOX1 promoter and α-factor leader sequence. Multi-copies insertion transformants were screened on G418 plates. After the induction by 1% methanol for 72 hours, the expression of Bm-TFF2 came up to the best quantity which was about 50 mg in 1L medium, and 80% saturation ammonium sulfate was suitable to collect the Bm-TFF2 protein, as identified by SDS-PAGE and Western blotting assay. The results showed that the plasmid of Bm-TFF2-pPIC9K was constructed successfully and expressed abundantly in eukaryotic expression system, which lies basis for researching further the biological activities and the relationship of structure and functions of Bm-TFF2.
  Yu Guo-Yu , XIANG Yang , ZHANG Hong-Yun , JIANG Ping , Lee Wen-Hui , ZHANG Yun and ZHANG Yong
  Bm-TFF2, a trefoil factor from the large-webbed bell toad (Bombina maxima), can stimulate cell migration and inhibit cell apoptosis. To study the structure-function relationship of Bm-TFF2, we constructed wild-type and mutated Bm-TFF2 plasmids and expressed recombinant proteins in E. coli. The wild-type Bm-TFF2 gene encoding mature peptide was obtained by RT-PCR, while the N-terminal, C-terminal and two arginine mutated Bm-TFF2 clones were constructed, and ligated into pET-32a(+) expression vectors. The fusion proteins were induced by IPTG at 37°C. The mutant Bm-TFF2 fusion proteins expressed mainly in the inclusion bodies. The mutant (TRX)/Bm-TFF2 could be purified by using Ni2+-chelating chromatography and reverse-phase HPLC from the inclusion body supernatant. The fusion proteins were analyzed by SDS-PAGE and Western blotting. The yield of mutant Bm-TFF2 fusion proteins of above 95% purity was about 20 mg/L. All three recombinant mutant proteins can promote the migration of AGS cells in a dose-dependent manner with no obvious activity difference.
 
 
 
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