cis- and trans-diammine-dichloroplatinum(II)-mediated cross-linking of chromosomal non-histone proteins to DNA in HeLa cells

The cross-linking of chromosomal non-histone proteins to DNA in isolated nuclei or intact HeLa cells exposed to different concentrations of cis- and trans-diamminedi-chloroplatinum(II) (cis- and trans-DDP) for various time intervals was investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunochemical methods. The immunochemical techniques revealed that both the 0.35 M sodium chloride insoluble and soluble chromosomal non-histone proteins were cross-linked to the DNA by both isomers. The action of cis- and trans-DDP was reversed and/or blocked by thiourea or 2-mercaptoethanol. Pretreatment of isolated nuclei or chromatin with iodoacetamide or N-ethylmaleimide did not prevent the DNA-protein cross-linking.