G-A mismatches are non-canonical base pairs that widely occur in native nucleic acids. They have been found to be functionally important in adopting unusual structures. In this paper, G-A mispairing was studied by Ram...G-A mismatches are non-canonical base pairs that widely occur in native nucleic acids. They have been found to be functionally important in adopting unusual structures. In this paper, G-A mispairing was studied by Raman spectral characterization of Polyadenylic acid （PolyA）, Polyguanylic acid （PolyG） and their equimolar mixture in solution of 0.08 mol/L Na^＋, pH7.0. The experiment showed the following three results. （1） At the experimental conditions used in the present work, PolyA and G A complexes existed as single-stranded and double-stranded helix of A form, respectively. And PolyG mainly occurred to be anti-parallel quadruplex conformers. （2） The formation of G A complexes, on one hand strengthened parts of base stacking interactions especially for PolyG, leading to Raman hypochromism effect with some corresponding bands shifting, and on the other hand weakened other base stacking interactions especially for PolyA to a certain degree. During this process, the backbone of PolyG underwent a significant change, but PolyA still conserved its main chain conformation. （3） The formation of G A complexes was stabilized by two interbase hydrogen- bond interactions （i.e. N6H2（A）-N3 （G） and N7 （A）--N2H2（G）） and a third hydrogen bond between O2^＋ （G） and N6 （A）. The third hydrogen bond was responsible for the remarkable changes of PolyG backbone conformation.展开更多
The electron transfer reaction of triplet menadione (3MQ?) with polyguanylic acid (polyG) in CH3CN rich (97%) solution was investigated by 248 nm(KrF) laser flash photolysis.The transient absorption spectra and kineti...The electron transfer reaction of triplet menadione (3MQ?) with polyguanylic acid (polyG) in CH3CN rich (97%) solution was investigated by 248 nm(KrF) laser flash photolysis.The transient absorption spectra and kinetics obtained from the interaction of 3MQ? with polyG demonstrated that the primary radical ion pair,radical cation of polyG and radical anion of me-nadione can be detected simultaneously.The results demonstrated that the reaction rate con-stant of 3MQ? with polyG is almost equal to that of 3MQ? with dGMP.展开更多
基金Project supported by the Natural Science Foundation of Guangdong Province, China （Grant No 021093） and Key-stone Science and Technology Foundation of Guangdong Province, China （Grant No 2KM04502S）.
文摘G-A mismatches are non-canonical base pairs that widely occur in native nucleic acids. They have been found to be functionally important in adopting unusual structures. In this paper, G-A mispairing was studied by Raman spectral characterization of Polyadenylic acid （PolyA）, Polyguanylic acid （PolyG） and their equimolar mixture in solution of 0.08 mol/L Na^＋, pH7.0. The experiment showed the following three results. （1） At the experimental conditions used in the present work, PolyA and G A complexes existed as single-stranded and double-stranded helix of A form, respectively. And PolyG mainly occurred to be anti-parallel quadruplex conformers. （2） The formation of G A complexes, on one hand strengthened parts of base stacking interactions especially for PolyG, leading to Raman hypochromism effect with some corresponding bands shifting, and on the other hand weakened other base stacking interactions especially for PolyA to a certain degree. During this process, the backbone of PolyG underwent a significant change, but PolyA still conserved its main chain conformation. （3） The formation of G A complexes was stabilized by two interbase hydrogen- bond interactions （i.e. N6H2（A）-N3 （G） and N7 （A）--N2H2（G）） and a third hydrogen bond between O2^＋ （G） and N6 （A）. The third hydrogen bond was responsible for the remarkable changes of PolyG backbone conformation.
基金the National Natural Science Foundat ion of China(Grant Nos.20133020&39830090) the Photo Science&Technology Research Foundat ion of Science and Technology Committee of Shanghai.
文摘The electron transfer reaction of triplet menadione (3MQ?) with polyguanylic acid (polyG) in CH3CN rich (97%) solution was investigated by 248 nm(KrF) laser flash photolysis.The transient absorption spectra and kinetics obtained from the interaction of 3MQ? with polyG demonstrated that the primary radical ion pair,radical cation of polyG and radical anion of me-nadione can be detected simultaneously.The results demonstrated that the reaction rate con-stant of 3MQ? with polyG is almost equal to that of 3MQ? with dGMP.
