Effects of rice peptide YGEGSSEEG on improving endothelial cell injury induced by tumor necrosis factor / 中国药理学通报

Aim To investigate the peptides and its protection for vascular endothelial cells, derived from the absorbed components of rice α-globulin,which was shown to be effective in anti-atherosclerosis. Methods The amino acid sequence was purified by gel chro-matography and RP-HPLC, and determined by ESI/MS. Then the peptide was chemically synthesized. Hu-man umbilical vein endothelial cell injury model was induced by tumor necrosis factor-α. The cell viability was measured by cell counting kit to screen the appro-priate peptide intervention concentration. The apoptotic rate was detected by flow cytometry. Bcl-2, Bax, p-p38, vascular cell adhesion molecule and the protein expression level of NF-κB signaling pathway were de-tected by Western blot and immunofluorescent stai-ning. Results Apoptosis of HUVECs induced by TNF-α was significantly increased by YGEGSSEEG, which also regulated expression of Bcl-2/Bax proteins and inhibited phosphorylation of p38 protein. Besides, the peptide suppressed the production of VCAM-1, ICAM-1 and activation of NF-κB pathway. While it did not significantly improve the oxidative stress response in HUVECs. Conclusion Peptide YGEGSSEEG pro-tects vascular endothelial cells through suppressing ap-optosis and expression of adhesion molecules.

Hydrodynamic properties of a– globulin from Sesamum indicum L.

The protein α-globulin from Sesamum indicum L. has been characterised for its size and shape using various chemical, physico-chemical and hydrodynamic properties. The protein has an S of 12·8, D 20,w of 4·9 × 10-7 cm2/sec and a partial specific volume of 0·725 ml/g in the native state. The intrinsic viscosity of the protein was determined to be 3·0 ml/g indicating it to be globular in shape. The molecular weight of the protein as determined by various approaches in analytical ultracentrifugation varies from 2·6–2·74 × 105. The molecular weight from sedimentation equilibrium yields a value of 2·74 × 105 in the native state and a value of 19000 in the dissociated and denatured state in 6 Μ guanidine hydrochloride. The evaluation of frictional ratios using Stokes radius and results from electron microscopy confirms the protein to be globular in shape. The protein consists of at least 12–14 subunits. The evaluation of hydrophobic parameters and energetics of interaction of subunits indicate that the protein is stabilized predominantly by hydrophobic interactions.

Partial specific volumes and interactions with solvent components of α -globulin from Sesamum indicum L. in urea and guanidine hydrochloride.

The interaction of α-globulin with urea/guanidine hydrochloride was investigated by determining the apparent partial specific volumes of the protein in these solvents. The apparent partial specific volumes were determined both under isomolal and isopotential conditions. The preferential interaction parameter with solvent components calculated were 0.08 and 0.1 g of urea and guanidine hydrochloride respectively per g protein. In both the cases the interaction was not preferential with water. The total binding of denaturant to α-globulin was calculated both for urea and guanidine hydrochloride and the correlation between experimentally determined number of mol of denaturant bound per mol of protein and the total number of peptide bonds and aromatic amino acids were found to be in excellent agreement with each other. The changes in volume upon transferring α-globulin from a salt solution to 8 Μ urea and 6 Μ guanidine hydrochloride were also calculated.

Studies on the conformation of a-globulin from Sesamum indicum L. in cationic and nonionic detergents.

The circular dichroic spectra of a-globulin from Sesamum indicum L. was recorded in the presence of cetyltrimethyl ammonium bromide, Triton X-100 and Brij-36T. The protein in 0.2 Μ phosphate buffer pH 7.4 had about 25% β-structure and 5% α-helix, the rest being aperiodic or irregular structure and a-helix, structure was increased by cationic detergent cetyl trimethyl ammonium bromide. But, the increase in α-helix content was much less than that induced by an anionic detergent, sodium dodecyl sulphate. In non-ionic detergent like Brij-36T and Triton X-100, specific β-structures like II-β and I-β were formed along with changes in α-helical and aperiodic structures. These results suggest that the protein has a fairly labile quaternary structure.