The DNA binding properties of two new platinum cent pounds, cis-[Pt(L)(2)Cl-2]. 2H(2)O where L is 5(6)-non/ chlorosubstincted-2-hydroxymethylbenzimidazole, were examined and compared with cisplatin. The platinum compounds (compounds I and II) were used to modify, DNA, which was then used in electrophoretic mobility shift assays with the high mobility group (HMG)-domain protein, HMG1. The DNA platinated with these compounds was specifically recognized by HMG1. It was concluded that the adducts formed by compounds I and II distort the DNA in a manner similar to cisplatin diadducts. (C) 1997 Elsevier Science Inc.