Kinetics of Formation of Deoxyribonucleic Acid Cross-Links by 4'-( Aminomethyl)-4,5',8-trimethylpsoralen~

If a mixture of T4 deoxyribonucleic acid (DNA) and 4'-(aminomethyl)-4,5',8-trimethylpsoralen is irradiated with two closely spaced pulses of long-wave UV laser light, the resulting cross-linking is dependent on the time delay between the pulses. As the delay lengthens to 1 ps, a rise in the number of cross-links is observed which follows first-order