Chromatographic change in histone H3-H4 preparations during short term storage and its reversal by bisulfite

Chicken erythrocyte histone H3-H4 preparations stored at 4 degrees in 50 mM sodium acetate (pH 5.0) exhibit altered gel chromatographic properties that are detectable within 2 days. After 5-7 days, material with chromatographic properties of the H3-H4 tetramer is absent, but the H3 and H4 polypeptides are intact, as judged by gel electrophoresis. The change in chromatographic properties results from an oxidation reaction: The change is accelerated by bubbling oxygen through H3-H4 preparations, and it is reversed by exposure to dithiothreitol. Because chicken erythrocyte H3 contains a single cysteine residue the oxidation reaction is intermolecular disulfide bond formation between H3 molecules. High molecular weight aggregates formed by the H3 dimers and some histone H4 probably are the same aggregates observed but unexplained by other workers. The H3-H4 tetramer can be regenerated by exposure of aged preparations to bisulfite, presumably as a result of cleavage of disulfide bonds and formation of S-sulfonated H3.