Speck W T, Rosenkranz S, Rosenkranz H S
Biochim Biophys Acta. 1976 Jun 2;435(1):39-44. doi: 10.1016/0005-2787(76)90189-1.
Illumination of DNA in the presence of riboflavin results in an increase in buoyant density and a decrease in the temperature of the thermal helix-coil transition (Tm). The increase in buoyant density is maintained even after thermal denaturation, which indicates that it reflects a chemical alteration of a DNA base (presumably guanine). beta-Carotene, a quencher of singlet oxygen, inhibits the increase in buoyant density but it prevents only partially the decrease in Tm. This is taken as an indication that the photo-induced alteration of the DNA structure is due to more than one reaction. Illumination of DNA in the presence of methylene blue also causes an increase in buoyant density , but this increase is not retained upon thermal denaturation.
在核黄素存在的情况下对DNA进行光照会导致浮力密度增加以及热螺旋-线圈转变温度（Tm）降低。即使经过热变性后，浮力密度的增加仍会持续，这表明它反映了DNA碱基（可能是鸟嘌呤）的化学改变。β-胡萝卜素是单线态氧的猝灭剂，它能抑制浮力密度的增加，但只能部分阻止Tm的降低。这表明DNA结构的光诱导改变是由多种反应引起的。在亚甲蓝存在的情况下对DNA进行光照也会导致浮力密度增加，但这种增加在热变性后不会保留。
