Secondary structure of nucleic acids in the folded chromosome from E. coli.
The circular dichroism of membrane-free folded chromosomes from E. coli was measured and analyzed. The spectrum can be explained as a simple linear combination of the individual spectra of E. coli RNA, and E. Coli DNA in the B form. No contribution from A form or C form DNA was detected. There was evidently some real variation in the ratio of the two nucleic acids from preparation to preparation, but the average value was 24% RNA and 76% DNA. No significant light scattering was observed and the analyses indicated no contribution to the circular dichroism from scattering artifacts. Apparently, combining DNA, RNA, and protein into membrane-free folded chromosomes does not change the secondary structure of the DNA or RNA from that found for the free nucleic acid in the same solvent system.
D002876:Chromosomes, Bacterial / Q000648:ultrastructure*; D002942:Circular Dichroism; D004269:DNA, Bacterial; D004926:Escherichia coli / Q000648:ultrastructure*; D009690:Nucleic Acid Conformation; D012329:RNA, Bacterial; D012542:Scattering, Radiation; D013056:Spectrophotometry, Ultraviolet; D014466:Ultraviolet Rays
D004269:DNA, Bacterial; D012329:RNA, Bacterial