Infrared spectrum of deoxyribonucleic acid. Effects of base composition and of N15-substitution.

Abstract

Abstract Infrared absorption spectra have been observed in the 4000–500 cm−1 region of deuterated and undeuterated films of deoxyribonucleic acids (DNA’s) obtained from Micrococcus lysodeikticus (guanine plus cytosine content or GC content 72%), from Bacille de Calmette-Guérin (GC 65%), from Pseudomonas aeruginosa (GC 65%, 15N-substituted), from calf thymus (GC 44%), and from Cancer borealis (GC 3%). Of the undeuterated DNA, 14 absorption bands have been assigned to the GC pair and 17 absorption bands to the adenine-thymine (AT) pair. Of the deuterated DNA, 19 absorption bands have been assigned to the GC pair and 16 to the AT pair. For 4 bands of undeuterated DNA and 13 bands of deuterated DNA, appreciable 15N isotopic shifts have been observed. A discussion has been given of a few of these bands on the basis of the observed 15N shift and some other data.