Using the ns pulse radolysis, we studied the characteristic absorption spectrum and kinetic decay of cytosine anion radical (Cyt). Reslults showed that the characteristic absorption of Cyt’ was located at λ=355±...Using the ns pulse radolysis, we studied the characteristic absorption spectrum and kinetic decay of cytosine anion radical (Cyt). Reslults showed that the characteristic absorption of Cyt’ was located at λ=355±5 nm, and decayed following the first order kinetics with T1/2=265 ns at pH=7.0. The decay,became slower and T1/2 rapidly rised with the increment of pH value, Cyt’protonated at C6 in acidic solution, and the characteristic absorption was located at λ=310±5 nm,and decayed following the second order kinetics: Cyt’ protonated at N3 in aqueous solution of pH≥7, and the characteristic absorption was located at λ=295±5 nm, and decayed following the second order kinetics.展开更多
Photochemical reactions of 4-nitroquinoline 1-oxide(4NQO) with methionine-containing dipeptides Met-Met, Ala-Met, Met-Lue and Met-Gly have been studies by using 248 nm laser flash photolysis. The formation of α-alkyl...Photochemical reactions of 4-nitroquinoline 1-oxide(4NQO) with methionine-containing dipeptides Met-Met, Ala-Met, Met-Lue and Met-Gly have been studies by using 248 nm laser flash photolysis. The formation of α-alkyl radicals was observed, and their rate constants of formation were obtained. The reaction mechanism that the α-alkyl radicals produced via an electron transfer process between triplet 4NQO and methionine-containing dipeptide was proposed.展开更多
文摘Using the ns pulse radolysis, we studied the characteristic absorption spectrum and kinetic decay of cytosine anion radical (Cyt). Reslults showed that the characteristic absorption of Cyt’ was located at λ=355±5 nm, and decayed following the first order kinetics with T1/2=265 ns at pH=7.0. The decay,became slower and T1/2 rapidly rised with the increment of pH value, Cyt’protonated at C6 in acidic solution, and the characteristic absorption was located at λ=310±5 nm,and decayed following the second order kinetics: Cyt’ protonated at N3 in aqueous solution of pH≥7, and the characteristic absorption was located at λ=295±5 nm, and decayed following the second order kinetics.
文摘Photochemical reactions of 4-nitroquinoline 1-oxide(4NQO) with methionine-containing dipeptides Met-Met, Ala-Met, Met-Lue and Met-Gly have been studies by using 248 nm laser flash photolysis. The formation of α-alkyl radicals was observed, and their rate constants of formation were obtained. The reaction mechanism that the α-alkyl radicals produced via an electron transfer process between triplet 4NQO and methionine-containing dipeptide was proposed.
