title: Mechanisms of chromosome banding. VII. Interaction of methylene blue with DNA and chromatin.
abstract: The binding of methylene blue to DNA and chromatin treated in various ways was examined by equilibrium dialysis. The maximum r value (moles of bound dye/mole of nucleotide) was 1.0 for DNA, 0.6 for unfixed chromatin, and 0.83 for chromatin fixed in methanol-acetic acid. When fixed chromatin was treated with saline-citrate at 60 degrees C for 3 hours, as used for G-banding chromosomes, the r value decreased from 0.83 to 0.55. When unfixed chromatin was treated as for R-banding the r values also dropped. Equilibrium dialysis indicated there was no disproportionate increase of dye binding as the concentration of DNA increased. -- These results, and others, suggest that some of the Giemsa negative regions of G- and R-banded chromosomes are due to the denaturation of non-histone proteins so that they more effectively cover the DNA and prevent side binding of the thiazin dyes.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002843:Chromatin; D002875:Chromosomes; D004247:DNA; D004347:Drug Interactions; D008751:Methylene Blue; D051379:Mice; D013194:Staining and Labeling
chemical_list: D002843:Chromatin; D004247:DNA; D008751:Methylene Blue