Studies with
N-Pyrenemaleimide, a probe which binds to H3 among
histones and
tryptophan residues of nonhistone
proteins and subsequently emits fluorescence, showed that during developing
cardiac hypertrophy, conformational changes due to
DNA-
histone interactions may be maximum at an early stage of
hypertrophy (17%
hypertrophy) while the changes due to non-
histone protein(s) interactions may be maximum at a latter stage (28%
hypertrophy). In vitro transcription analysis in isolated nuclei obtained from normal and hypertrophic hearts showed that nuclei obtained from 40% hypertrophic hearts had a maximum incorporation ability than nuclei obtained from 17% or 28% hypertrophic hearts. Analysis of
histones and 0.35 M NaCl extractable
nuclear proteins by single dimensional
polyacrylamide gel electrophoresis did not reveal any changes in these
proteins when obtained from normal and different stages of hypertrophic hearts.
DNase I sensitivity studies with nuclei obtained from normal and hypertrophic hearts and with reconstituted nuclei, showed that changes in 0.35 M NaCl extractable
proteins may contribute to the respective
DNase I sensitivity of various hypertrophic nuclei. These studies also indicated that though nuclei obtained from 40% hypertrophic hearts showed maximum incorporation during in vitro transcription, the
DNase I sensitivity is maximum only in nuclei obtained from 28% hypertrophic hearts and not from 40% hypertrophic hearts.