Differences in chromatin from normal and leukemic human cells as shown by digestion with restriction nucleases.

Restriction endonuclease MspI digested significantly more than HpaII the DNA and chromatin from normal and leukemic human cells, although both enzymes digested DNA more than chromatin. Moreover, DNA and chromatin from normal cells showed higher digestion by HpaII compared to DNA and chromatin from leukemic cells indicating higher frequency of Cm5CCG in latter DNA. EcoRII and BstNI, which have the recognition sequence CCATGG but cut at different points, digested all DNAs significantly, as did BstNI for chromatin from all sources. However, chromatin from normal cells showed only limited digestion by EcoRII which significantly digested chromatin from leukemic cells. This could result from subtle differences in the conformation of normal and leukemic cell chromatin involving recognition sequences for EcoRII.