Native state of high mobility group chromosomal proteins 1 and 2 is rapidly lost by oxidation of sulfhydryl groups during storage.

Oxidized forms of non-histone chromosomal proteins high mobility group 1 (HMG1) and HMG2 were detected by high-pressure liquid chromatography of preparations stored at 4 degrees C for 1 day. The oxidized form of each was found to have two free sulfhydryl groups, while the freshly prepared native form of each contained four. The native, reduced state could be maintained during storage by the addition of ethylenediaminetetraacetic acid or reducing agents.