31P magnetic resonance of DNA in nucleosome core particles of chromatin.

The 31P magnetic resonance spectrum of nucleosome cores from calf thymus nuclei has been measured. The spectrum consists of a single symmetric line, with a maximum second component of 5%. It is argued that this reflects a single average state of the DNA backbone, and does not support models that invoke backbone kinking at a frequency of 1 in 10 base pairs.