低功率密度He-Ne激光诱变固体DNA的拉曼光谱分析

Analyses on Raman Spectrum of Calf Thymus DNA Induced by Low-power Density He-Ne Laser

低功率密度的He-Ne激光照射DNA固体纤维后,构象仍为A型。照射时间很短时,激光对磷酸骨架结构基本无影响,对氢键和碱基有轻微损伤。随着照射时间延长,部分磷酸二酯键和氢键断裂。继续照射,激光先是对DNA的损伤有所减少,然后又使DNA的损伤加剧。但磷酸骨架基团损伤程度减小的时间早于氢键损伤程度减小的时间。在较长时间照射后激光对DNA损伤程度反而降低的机制目前并不清楚。激光对大部分碱基的影响是先破坏与DNA垂直的碱基-碱基堆积相互作用,再使碱基之间氢键受损和断裂。

The conformation of the DNA solid fiber is still A-type after it was irradiated by low-power density He-Ne laser. But the conformation has the minor damage when the laser irradiation time lengthened. After laser irradiating of a short time, the experimental results proved that the laser irradiation had hardly any effect on phosphoric acid skeleton structure and slightly damaged the hydrogen bonds and the bases. With the extended laser irradiation time, some of the di-phosphate ester key O-P-O and of the hydrogen bonds were broken. Continued laser irradiation, the DNA damage induced by laser reduced firstly, then its damage was aggravated. But the time when extent of damage of phosphoric acid skeleton groups reduced is earlier than the time when extent of damage of hydrogen bond reduced. The mechanism which the DNA damage reduced instead increased with laser irradiation for a longer time is not clear. First the laser destroyed the interaction of base-base which perpendicular with DNA for the majority of basic groups, then made hydrogen bonds of the base damaged and cut off.