ULTRAVIOLET PHOTOCHEMISTRY OF THYMIDYLYL- (3]TO5]) -THYMIDINE
ULTRAVIOLET PHOTOCHEMISTRY OF THYMIDYLYL- (3]TO5]) -THYMIDINE
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DOI：
10.1016/s0022-2836(64)80223-0
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发表时间：
1964-01-01
影响因子：
5.6
通讯作者：
LEBLANC, JC
中科院分区：
文献类型：
--
作者：
JOHNS, HE;PEARSON, ML;LEBLANC, JC
用波长范围为225至289 m[mu]的单色光照射32 P标记的TpT+，产生四种色谱可分离的光产物。两种异构体二聚体TpT 1和TpT 2与TpT接近平衡，在225 m[mu]处二聚体形式为2.5%，在289 m[mu]处为95%。二聚体的相对产率为5：1，且与波长无关。未知的光产物之一，TpT 4，它具有在325 m[mu]处的最大吸收，是由TpT不可逆地产生的，其产率与最不丰富的二聚体TpT 2相当。这种光产物又可以通过313 m[mu]的照射转化为第二个未知的TpT 3。TpT 3可以通过在240 m[mu]下再照射而再转化为TpT 4。由于TpT 3和TpT 4在257 m[mu]处具有消光，其约为一个胸腺嘧啶的三分之一，因此很可能在这两种化合物中两个胸腺嘧啶部分都被改变。没有一种光产物被毒液磷酸二酯酶水解;这也表明所有四种光产物中的胸腺嘧啶部分都连接在一起。没有一种光产物在85[degree]C和pH 1或13时是完全稳定的。没有确凿的证据表明TpT的热水合光产物的生产已经found. The横截面和量子产率的生产从TpT，逆转的二聚体TpT，和TpT 4和TpT 3的相互转换已被确定为波长的函数，使用色谱纯化的光产物。剂量-效应曲线的数学分析允许计算横截面。
Irradiation of 32P labelled TpT+ by monochromatic light in the wavelength range 225 to 289 m[mu] results in the production of four chromatographically separable photoproducts. Two isomeric dimers, TpT1 and TpT2, approach an equilibrium with TpT with 2.5% in the dimer form at 225 m[mu] and 95% at 289 m[mu]. The relative yields of the dimers are 5;1 and independent of wave-length. One of the unknown photoproducts, TpT4 , which has an absorption maximum at 325 m[mu], is produced irreversibly from TpT at a yield comparable to the least plentiful dimer, TpT2. This photoproduct can in turn be converted to a second unknown, TpT3, by irradiation at 313 m[mu]. TpT3 can be reconverted to TpT4 by re-irradiation at 240 m[mu]. Since TpT3 and TpT4 have an extinction at 257 m[mu] which is about one-third of one thymine, it is likely that in both these compounds both thymine moieties are altered. None of the photoproducts in hydrolysed by venom phosphodiesterase; this also suggests that the thymine moieties in all four photoproducts are joined together. None of the photoproducts is completely stable at 85[degree]C at pH 1 or 13. No conclusive evidence for the production of a heat-hydrate photoproduct of TpT has been found. The cross-sections and quantum yields for the production of photoproducts from TpT, the reversal of dimers to TpT, and the interconversion of TpT4 and TpT3 have been determined as a function of wavelength, using chromato-graphically purified photoproducts. Mathematical analysis of the dose-effect curves permits the calculation of the cross-sections.