Gutter B, Speck W T, Rosenkranz H S
Biochim Biophys Acta. 1977 Mar 18;475(2):307-14. doi: 10.1016/0005-2787(77)90021-1.
Illumination (white light: 300-750 nm) of DNA in the presence of hematoporphyrin (less than or equal to 5-10 (-4) M) results in selective degradation of the guanine moiety. DNA so illuminated exhibits physical chemical properties (lowered sedimentation coefficients, lower temperatures of helix-coil transitions, increased buoyant density values) consistent with single-chain scissions (and the generation of single-stranded regions) which presumably are secondary to the photodegradation of the guanine residue. Illumination of DNA in the presence of low levels of hematoporphyrin (greater than or equal to 2.5 - 10 (-4) M) results in a biopolymer exhibiting all of the physical properties described above with the exception of a lowered sedimentation coefficient; on the contrary such DNA is aggregated. Of the four usual deoxynucleosides irradiated in the presence of hematoporphyrin, only deoxyguanosine is destroyed.
在血卟啉（小于或等于5 - 10（-4）M）存在的情况下，用白光（300 - 750纳米）照射DNA会导致鸟嘌呤部分的选择性降解。如此照射的DNA表现出与单链断裂（以及单链区域的产生）一致的物理化学性质（沉降系数降低、螺旋-卷曲转变温度降低、浮力密度值增加），推测这是鸟嘌呤残基光降解的继发结果。在低水平血卟啉（大于或等于2.5 - 10（-4）M）存在的情况下照射DNA会产生一种生物聚合物，其具有上述所有物理性质，但沉降系数降低除外；相反，这种DNA会发生聚集。在血卟啉存在的情况下照射四种常见的脱氧核苷，只有脱氧鸟苷会被破坏。
