键联于核酸的激发态水溶铜卟啉共振拉曼光谱研究

A Study of Resonance Raman Spectrum of Electronically Excited Water-Soluble Copper Porphyrin Bound to Nucleic Acids

本文测量了键联于核酸的激发态水溶铜卟啉共振拉曼光谱.结果表明,位于1550cm^(-1)和1346cm^(-1)附近的两条谱带归属于受激铜卟啉拉曼带,其强度与核酸和铜卟啉的种类、核酸所含的(AT)_n结构和受激铜卟啉沟槽键联于核酸的能力有关.文中对插入DNA中GC位置上的基态铜卟啉在受激状态下能沟槽键联于—ATAT一位置这一现象作了定性的解释.

The resonance Raman spectrum of several electronically excited copper porphyrins bound to different kinds of nucleic acids have been measured with a 416 nm pulse laser line made of an H2 Raman shifter. The results show that two extra bands nearby 1550cm-1 and 1346cm-1 belong to electronically excited copper porphyrins Raman bands. The intensity of these Raman bands is found to be dependent on the kinds of nucleic acids or copper porphyrins, and determined by the sites where(AT)n is present in the nucleic acids as well as by the ability of how close the porphyrin can be bound to the nucleic acid bases preferably by groove binding. The fact that some porphyrins intercalate at GC sites in DNA when they are in their ground state and bound to -ATAT- sites by groove upon pulse laser resonant excitation has been explained qualitatively by the 'hopping' mechanism. Either a change of porphyrin geometry or a variation of electrical binding stability to nucleic acid is the possible reason why hopping occurs.