Oroskar A, Olack G, Peak M J, Gasparro F P
Center for Mechanistic Biology and Biotechnology, Argonne National Laboratory, IL 60439.
Photochem Photobiol. 1994 Dec;60(6):567-73. doi: 10.1111/j.1751-1097.1994.tb05149.x.
The photochemistry of 4'-aminomethyl-4,5',8-trimethylpsoralen (AMT) with poly(dA-dT) and calf thymus DNA was studied. The extent of photoadduct formation and the distribution of photoadducts (3,4- and 4',5'-monoadducts and crosslinks) were determined by liquid scintillation analysis and HPLC, respectively. The adducts were characterized on the basis of their UV absorption spectra and mass spectral analysis. The high DNA binding constant for AMT (1.5 x 10(5) M-1) led to a high fraction of intercalated molecules, which contributed to the high level of AMT photoadduct formation, as many as 102 adducts per kilobase pair. In addition, there is a distinct difference in the adduct distribution compared to the previously studied 8-methoxypsoralen (8-MOP). Under the conditions employed for the photochemical studies, virtually all of the AMT molecules in solution are intercalated, occupying 25% of the base pair sites. Under similar conditions, 8-MOP molecules occupied 10 times fewer sites. Thus, for AMT, DNA base pair sites other than 5'TA, the well-characterized strong binding for psoralens in general, are an additional target for photomodification, which results in the formation of a higher percentage of monoadducts. The proportion of photoadducts formed was virtually independent of AMT concentration and UVA (320-400 nm radiation) fluence.
研究了4'-氨甲基-4,5',8-三甲基补骨脂素（AMT）与聚（dA-dT）和小牛胸腺DNA的光化学性质。通过液体闪烁分析和高效液相色谱法分别测定了光加合物的形成程度和光加合物（3,4-和4',5'-单加合物及交联物）的分布。根据加合物的紫外吸收光谱和质谱分析对其进行了表征。AMT的高DNA结合常数（1.5×10⁵ M⁻¹）导致大量分子发生插入，这使得AMT光加合物形成水平较高，每千碱基对多达102个加合物。此外，与之前研究的8-甲氧基补骨脂素（8-MOP）相比，加合物分布存在明显差异。在光化学研究采用的条件下，溶液中几乎所有的AMT分子都发生了插入，占据了25%的碱基对位点。在类似条件下，8-MOP分子占据的位点少10倍。因此，对于AMT来说，除了5'TA（一般认为是补骨脂素特征性的强结合位点）之外的DNA碱基对位点也是光修饰的额外靶点，这导致形成更高比例的单加合物。形成的光加合物比例实际上与AMT浓度和UVA（320 - 400 nm辐射）通量无关。
