| Protein tyrosine nitration, a ubiquitous post-translational modification, is a special form of oxidative damage. Protein oxidation occurred in parallel with protein tyrosine nitration, can be detected by the increase of carbonyl. Protein tyrosine nitration and oxidation which could regulate protein structure and function have been found under conditions of nitrative/oxidative stress in a number of physiological and pathologic states.In this thesis, the effect of different buffers and pH on hemin-NO2--H2O2 system induced bovine serum albumin (BSA) nitration and oxidation was studied by using Western blotting, spectrophotometry and SDS-PAGE. The buffers including NaHCO3-CO2, Tris-HCl, PBS, Citrate-Citric acid and Hepes, which are commonly used in biochemistry and cell biology, were chosen. The results showed that BSA could be nitrated and oxidized by hemin-NO2--H2O2 system in all tested buffers, and the pH influence on BSA nitration was contrary to that of BSA oxidation: in pH range of 6.0-8.0, protein nitration was decreased with the increasing of pH, while protein oxidation was significantly increased. The extents of BSA nitration and oxidation were also different in the five buffers at pH7.0. For BSA nitration, Tris-HCl > PBS, Citrate-Citric acid, NaHCO3-CO2 > Hepes, while for BSA oxidation, NaHCO3-CO2, PBS > Citrate-Citric acid > Tris-HCl > Hepes. Further research indicated that buffers could reduce protein tyrosine nitration through inhibiting nitrite oxidation. The research mentioned above indicated that effect of buffers on hemin-NO2--H2O2 induced bovine serum albumin (BSA) nitration and oxidation was different. The higher efficiency of tyrosine nitration under acidic conditions, whereas oxidation rate increased at more alkaline pH. Noticeably, both tyrosine nitration and oxidation were at low level in Hepes, reminding us that using Hepes buffer is not a suitable media of cell culture or other in vitro experiments of antinitrative or antioxidative studies.
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