Temperature‐dependent cleavage of chromatin by micrococcal nuclease near the nucleosome center

Abstract
Digestion of nuclei at 4°C with micrococcal nuclease results in significant intranucleosomal cleavage compared to digestion conducted at 37°C. Employing nucleoprotein gel electrophoresis in one dimension followed by DNA electrophoresis in a second dimension, we demonstrate that such temperature‐sensitive, internal cleavage predominantly occurs about 20 bp from the nucleosome center. We suggest that lower temperatures reduce the stability of hydrophobic interactions within the histone octamer and lead to a conformational alteration in nucleosomes that is detected by micrococcal nuclease.