DNA and various proteins form complexes when exposed in vitro to β-propiolactone (BPL). These artificially produced “nucleoproteins” were detected by their increased sedimentation, decreased mobility in gels during electrophoresis, lowered buoyant density in CsCl and Cs2SO4 gradients, and increased retention on methyl-esterified albuminkieselguhr columns, compared with untreated DNA-protein mixtures and BPL-treated DNA alone. Initially, the complexes are soluble in ionic detergents, but during longer exposure to BPL a transition to an insoluble structure is observed. The chemical nature of the protein-DNA bonds is unknown. Since BPL is a powerful carcinogen, the possibility that the cross-linking of proteins to DNA plays a role in chemical oncogenesis is considered.

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This work was supported by the USPHS Grant CA 08959.

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