The Research Of Human Telomeric Sequences By Surface Enhanced Raman Spectroscopy

The formation, depolymerization and different structural change ofG-quadruplexe structures of Human telomere terminal sequence has a closerelationship with the occurrence and development of tumor process, which has animportant significance for the early detection and diagnosis of cancer. At present,researching on the formation and disassembly process of G-quadruplexe structuresunder the environment of different metal ions, the technical means such as CD,NMR, IR and X ray diffraction were used to be utilized. However, these technicalmeans have a certain limitations in detecting and studying the formation,depolymerization and different structural change of G-quadruplexe structure formedby nucleic acid sequence in the telomeric endsIn this paper, the G-quadruplexe structure of human telomeric sequences wasstudied by means of surface-enhanced resonance Raman scattering spectra. Basedon the results, the spectrum characteristics of different forms of G-quadruplexestructure in Raman spectrum were found. And then, the formation,depolymerization and different structural change of G-quadruplexe structures ofHuman telomere terminal sequence was detected by surface-enhanced resonanceRaman spectroscopy （SERRS） technology. Combined with the Tumors of cancercells amplification, the malignant tumor can be detected, which has importantsignificance for early cancer diagnosis.Firstly, nucleic acid molecular chemical bond vibration frequencies werecalculated by using of the DFT （Density functional theory） theoretical calculation method, and the calculated results of nucleic acid bases Raman spectral peaks werecharacterization. By comparing the experimental Raman spectra peak position withthe theoretical Raman spectrum peak position, we found that when the B3LYP/6-311⁺⁺G （D, P） act as the parameters on the base of vibration relative to B3LYP/6-31⁺⁺G （D, P） and B3LYP/6-311G （D, P） as calculation parameters used by theprevious researchers, the calculation results is more accurate. The theory of Ramanmapping and the actual base of Raman mapping has greater consistency, predictionof the Raman spectra of vibration frequency is very accurate and vibrationfrequency of the error is very small, less than3%.Finally, we studied the G-quadruplexe structures formed by four humantelomere sequence by means of CD and surface enhanced Raman spectroscopy,when Na⁺and K⁺existing under the conditions of the formation of G-quadruplexestructure. CD results showed that under the Na⁺and K⁺conditions, several differenthuman telomeric sequences can form anti-parallel-G-quadruplexe structure, but inthe Na⁺condition relative to in the K⁺under the condition, the sequence formedmore anti-parallel-G-quadruplexe structure. Surface enhanced Raman spectroscopyresults show that, in the presence of Na⁺,1325cm^-1and1353cm^-1contains a strongsignal peaks, they are all indications of telomeric sequences in guanine dG C2’ endo/syn vibration; and in the presence of K⁺,1384cm^-1contains a strong signal peaks, itrefers to a syndrome guanine dG （N2） C2’ endo/anti vibration in telomeresequences in, so we can get consistent results through the surface Ramanspectroscopy and CD chromatography。Under the condition of the existence of K⁺the sequences can form more homeopathic structure, so accord to the Raman signalstrength changes, it can determine telomere sequence structure changes. Because the surface enhanced Raman spectroscopy has higher sensitivity than CDchromatography, Studying the formation, depolymerization and different structuralchange of G-quadruplexe structures of Human telomere terminal sequence bymeans of the surface enhanced resonance Raman spectroscopy technology has avery high application value.