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Articles by Y. Feng
Total Records ( 3 ) for Y. Feng
  S Yu , B Zheng , X Zhao and Y. Feng

A bioinformatic screening of the genome of the thermophilic bacterium Fervidobacterium nodosum Rt17-B1 for ester-hydrolyzing enzymes revealed a putative bacterial esterase (FNE) encoded by Fond_1301 with typical GDSL family motifs. To confirm its putative esterase function, the FNE gene was cloned, functionally expressed in Escherichia coli, and purified to homogeneity. Recombinant FNE exhibited the highest esterase activity of 14,000 U/mg with p-nitrophenyl acetate (pNPC2) as substrate. The catalytic efficiency (kcat/Km) toward p-nitrophenyl acetate (C2) was approximately 120-fold higher than toward p-nitrophenyl butyrate (C4). No significant esterase activity was observed for the substrates with a chain length ≥C8. The monomeric enzyme has a molecular mass of 27.5 kDa and exhibits optimal activity around 75°C, at pH 8.5. Its thermostability is relatively high with a half-life of 80 min at 70°C, but less stable compared with some other hyperthermophilic esterases. A structural model was constructed using acetylesterase from Aspergillus aculeatus as a template. The structure showed an /β-hydrolase fold and indicated the presence of a typical catalytic triad consisting of a serine, aspartate, and histidine, which was verified by site-directed mutagenesis. Sequence analysis showed that FNE was only distantly related to other esterases. A comparison of the conserved motifs shared with GDSL proteins revealed that FNE could be grouped into GDSL family and was further classified as SGNH hydrolase.

  G-Z. He , Y-X. Chen , W-Y. Tian , Y. Feng , A-N. Wang , Y. Wei , Q.S. He and C.W. An
  This is the first case report of amebic dysentery due to infection of Entamoeba histolytica (E. histolytica) in a King Horseshoe bat. A fresh fecal sample was collected from a King Horseshoe Bat (Rhinolophus rex) and identified by microscopic examination, E. histolytica stool antigen detection kit, two PCR assays and DNA sequence analysis. A daily dose of 10 mg of metronidazole was given orally for 5 days and no amoeba was detected in the fecal sample after the treatment. The results of present study suggest that amoebiasis of bat should be monitored more closely in the future.
  S. J Wu , J Luo , K. T O'Neil , J Kang , E. R Lacy , G Canziani , A Baker , M Huang , Q. M Tang , T. S Raju , S. A Jacobs , A Teplyakov , G. L Gilliland and Y. Feng

Protein aggregation is of great concern to pharmaceutical formulations and has been implicated in several diseases. We engineered an anti-IL-13 monoclonal antibody CNTO607 for improved solubility. Three structure-based engineering approaches were employed in this study: (i) modifying the isoelectric point (pI), (ii) decreasing the overall surface hydrophobicity and (iii) re-introducing an N-linked carbohydrate moiety within a complementarity-determining region (CDR) sequence. A mutant was identified with a modified pI that had a 2-fold improvement in solubility while retaining the binding affinity to IL-13. Several mutants with decreased overall surface hydrophobicity also showed moderately improved solubility while maintaining a similar antigen affinity. Structural studies combined with mutagenesis data identified an aggregation ‘hot spot’ in heavy-chain CDR3 (H-CDR3) that contains three residues (99FHW100a). The same residues, however, were found to be essential for high affinity binding to IL-13. On the basis of the spatial proximity and germline sequence, we reintroduced the consensus N-glycosylation site in H-CDR2 which was found in the original antibody, anticipating that the carbohydrate moiety would shield the aggregation ‘hot spot’ in H-CDR3 while not interfering with antigen binding. Peptide mapping and mass spectrometric analysis revealed that the N-glycosylation site was generally occupied. This variant showed greatly improved solubility and bound to IL-13 with affinity similar to CNTO607 without the N-linked carbohydrate. All three engineering approaches led to improved solubility and adding an N-linked carbohydrate to the CDR was the most effective route for enhancing the solubility of CNTO607.

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