Electron microscopy of interphase chromosomes in situ; binding of permanganate to chicken erythrocytes.

From quantitative electron-microscope observations on the binding of permanganate to regions of erythrocytes and reticulocytes of known chemical composition, it is concluded that KMnO4, like phosphotungstic acid (PTA), binds preferentially to sites on proteins. Compared with PTA, KMnO4 binding exhibits less anomalous behaviour. The data support the hypothesis previously put forward that the 2 regions, or phases, in condensed chromatin differ in both molecular composition and concentration. The increase in binding to protein which occurs during nuclear haemolysis is interpreted in terms of protein-protein interaction in the chromatin of the intact cell.