Laser flash photolysis was used to investigate the photoinduced reactions of excited triplet bioquinone molecule duroquinone(DQ)with tryptophan(Trp)and tyrosine(Tyr)in acetonitrile-water(Me CN-H_(2)O)and ethylene glyc...Laser flash photolysis was used to investigate the photoinduced reactions of excited triplet bioquinone molecule duroquinone(DQ)with tryptophan(Trp)and tyrosine(Tyr)in acetonitrile-water(Me CN-H_(2)O)and ethylene glycol-water(EG-H_(2)O)solutions.The reaction mechanisms were analyzed and the reaction rate constants were measured based on Stern-Volmer equation.The H-atom transfer reaction from Trp(Tyr)to ^(3)DQ^(*)is dominant after the formation of^(3)DQ^(*)during the laser photolysis.For DQ and Trp in MeCN-H_(2)O and EG-H_(2)O solutions,^(3)DQ^(*)captures H-atom from Trp to generate duroquinone neutral radical DQH^(·),carboncentered tryptophan neutral radical Trp^(·)/NH and nitrogen-centered tryptophan neutral radical Trp/N^(·).For DQ and Tyr in Me CN-H_(2)O and EG-H_(2)O solutions,^(3)DQ^(*)captures H-atom from Tyr to generate duroquinone neutral radical DQH^(·) and tyrosine neutral radical Tyr/O^(·).The H-atom transfer reaction rate constant of^(3)DQ^(*)with Trp(Tyr)is on the level of 109 L·mol^(-1)·s^(-1),nearly controlled by diffusion.The reaction rate constant of^(3)DQ^(*)with Trp(Tyr)in Me CN/H_(2)O solution is larger than that in EG/H2O solution,which agrees with Stokes-Einstein relationship qualitatively.展开更多
基金supported by the National Natural Science Foundation of China (No.21673003)the National Major Scientific Instrument and Equipment Development Project (No.21927814)。
文摘Laser flash photolysis was used to investigate the photoinduced reactions of excited triplet bioquinone molecule duroquinone(DQ)with tryptophan(Trp)and tyrosine(Tyr)in acetonitrile-water(Me CN-H_(2)O)and ethylene glycol-water(EG-H_(2)O)solutions.The reaction mechanisms were analyzed and the reaction rate constants were measured based on Stern-Volmer equation.The H-atom transfer reaction from Trp(Tyr)to ^(3)DQ^(*)is dominant after the formation of^(3)DQ^(*)during the laser photolysis.For DQ and Trp in MeCN-H_(2)O and EG-H_(2)O solutions,^(3)DQ^(*)captures H-atom from Trp to generate duroquinone neutral radical DQH^(·),carboncentered tryptophan neutral radical Trp^(·)/NH and nitrogen-centered tryptophan neutral radical Trp/N^(·).For DQ and Tyr in Me CN-H_(2)O and EG-H_(2)O solutions,^(3)DQ^(*)captures H-atom from Tyr to generate duroquinone neutral radical DQH^(·) and tyrosine neutral radical Tyr/O^(·).The H-atom transfer reaction rate constant of^(3)DQ^(*)with Trp(Tyr)is on the level of 109 L·mol^(-1)·s^(-1),nearly controlled by diffusion.The reaction rate constant of^(3)DQ^(*)with Trp(Tyr)in Me CN/H_(2)O solution is larger than that in EG/H2O solution,which agrees with Stokes-Einstein relationship qualitatively.
