| Popis: |
To exploit sensitive, accurate and convenient detection techniques for nucleic acid sequences can help to overcome the defects of current fluorescence detection method. Raman spectroscopy represents one family of methods that may offer such potential. In this paper, G•C base pairs and C•U mispairs were studied by Raman spectral characterization of single-strand homopolynucleotides, i.e. polyguanylic acid (PolyG), polycytidylic acid (PolyC) and polyuridylic acid (PolyU), and their equimolar complexes PolyG•PolyC and PolyC•PolyU in solution of 0.14 M Na+, pH7.0. Both of the complexes were found to adopt A type conformation. Helix formation between complementary polynucleotides led to marked and characterisctic changes in frequency and intensity of Raman bands of the biopolymers. Spectral changes were also observed upon the formation of C•U mispairs. According to the Raman data, in C•U mispairs the C2=O of U was engaged in a hydrogen bond to the N4H2group of cytosine, while the uracil C4=O group is free. Some of the rC residues transformed from C3-endo/anti to C2-endo/anti conformation due to base mispairing.The results suggest that Raman spectroscopy provides detailed and highly sensitive information about both the structure of nucleic acids and their base composition, and has great potential for analysis of DNA sequences. |
