Insight into the mechanism of urea inhibit ovalbumin-glucose glycation by conventional spectrometry and liquid chromatography-high resolution mass spectrometry.

The inhibition effect of urea on ovalbumin (OVA) glycation was investigated, and the mechanism was evaluated through the changes in protein structure as well as glycation sites and average degree of substitution per peptide molecule (DSP) by conventional spectrometry and liquid chromatography-high resolution mass spectrometry (LC-HRMS). A urea concentration of 3 M was chosen as the optimum condition. Ultraviolet and fluorescence spectra suggested that both glycation and urea treatment could unfold the OVA, but urea inhibited the glycation-induced protein unfolding. Circular dichroism spectra showed that urea treatment could increase the ß-sheet content and reduce the α-helix content of OVA. LC-HRMS indicated that the number of glycation sites was reduced from 15 to 3, and DSP values decreased with urea treatment. In conclusion, urea could significantly inhibit the OVA-glucose glycation, and the sites competition as well as structure unfolding inhibition resulted from urea could be the main factors.

Gene expression and activities analysis of a new fusion protein (RGD) 3/tTF / 生物工程学报

To develop a new fusion protein (RGD)3/tTF for the therapy of the selective thrombosis of tumor blood vessels. The fused gene (RGD) 3/tTF was reconstructed by PCR, was cloned into vector pET22 b(+), and expressed in E. coli BL21 (DE3). The fusion protein was purified through Nickel-affinity chromatography column. The tTF activity of the fusion protein was detected by clotting assay and F X activation assay. The specific binding of (RGD) 3/tTF to alphavbeta3 was analyzed by indirect ELISA. The recombinant plasmid pET22 b(+)/(RGD)3/tTF was obtained and expressed in E. coli BL21 (DE3). The purified fusion protein could induce blood coagulation, activiate F X. The ability of (RGD) 3/tTF binding specifically to alphavbeta3 was increased by 32%, compared with RGD/tTF. A new fusion protein (RGD) 3/tTF was successfully expressed in E. coli BL21 (DE3). The expressed proteins retained tTF activity and showed a higher binding to alphavbeta3 than that of RGD/tTF.