Digestion of centromeric DNA from each human metaphase chromosome by the 6 bp-restriction enzyme StuI.

Although 6 bp-restriction endonucleases infrequently cut DNA, we describe in this paper the banding pattern induced by one of them, StuI (AGGCCT), on fixed human chromosomes. This enzyme is the first 6 bp-restriction endonuclease demonstrated to be able to digest human heterochromatin. It causes the extraction of two families of repeated DNA, the alpha satellite DNA and the 3.4 kb HaeIII family (DYZ1). On the other hand, digestions with StuI and with another two enzymes, HinfI and RsaI, have established the distribution of sequences within the heterochromatic block of chromosome 3.