A pepsin-revealed material possibly related to chromosomal banding.

The enzymes pepsin, alpha-chymotrypsin, trypsin, RNase and DNase were applied to preparations of human metaphase chromosomes before staining to study whether dissociable materials related to the formation of G-, Q- and C-bands would be seen. Treatment with active pepsin but not the other enzymes revealed material with ribonucleo-protein properties which dissociated from the chromosomes and formed a halo.--Lateral extensions from the chromatids stretched to the rim of the halo and appeared at positions corresponding to G-bands. A G-band may be defined as a ring of stable chromatid-matrix binding at positions where the chromatids coil to form lateral extensions.