[Microcalorimetric study of intact nucleoproteins]

It has been shown that melting of native chromatin complex in tissues and cells is a one stage process with transition parameters Tm = 82 +/- 1 degrees C, delta Tm = 6 degrees C and Qm = (24 +/- 3) cal/g DNA. A conclusion is made that the difference in melting temperatures of chromatin complex and DNA, which is 12 cal/g DNA, corresponds to the melting of secondary and tertiary structures of chromatin. It is shown the destruction of significant part of the secondary and tertiary structures of chromatin by the chromatin complex isolation from tissues and cells.