1ihh

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Revision as of 19:54, 24 November 2007

2.4 ANGSTROM CRYSTAL STRUCTURE OF AN OXALIPLATIN 1,2-D(GPG) INTRASTRAND CROSS-LINK IN A DNA DODECAMER DUPLEX

Overview

(1R,2R-Diaminocyclohexane)oxalatoplatinum(II) (oxaliplatin) is a, third-generation platinum anticancer compound that produces the same type, of inter- and intrastrand DNA cross-links as cisplatin. In combination, with 5-fluorouracil, oxaliplatin has been recently approved in Europe, Asia, and Latin America for the treatment of metastatic colorectal cancer., We present here the crystal structure of an oxaliplatin adduct of a DNA, dodecanucleotide duplex having the same sequence as that previously, reported for cisplatin (Takahara, P. M.; Rosenzweig, A. C.; Frederick, C., A.; Lippard, S. J. Nature 1995, 377, 649-652). Pt-MAD data were used to, solve this first X-ray structure of a platinated DNA duplex derived from, an active platinum anticancer drug other than cisplatin. The overall, geometry and crystal packing of the complex, refined to 2.4 A resolution, are similar to those of the cisplatin structure, despite the fact that the, two molecules crystallize in different space groups. The platinum atom of, the [Pt(R,R-DACH)](2+) moiety forms a 1,2-intrastrand cross-link between, two adjacent guanosine residues in the sequence 5'-d(CCTCTGGTCTCC), bending the double helix by approximately 30 degrees toward the major, groove. Both end-to-end and end-to-groove packing interactions occur in, the crystal lattice. The latter is positioned in the minor groove opposite, the platinum cross-link. A novel feature of the present structure is the, presence of a hydrogen bond between the pseudoequatorial NH hydrogen atom, of the (R,R)-DACH ligand and the O6 atom of the 3'-G of the platinated, d(GpG) lesion. This finding provides structural evidence for the, importance of chirality in mediating the interaction between oxaliplatin, and duplex DNA, calibrating previously published models used to explain, the reactivity of enantiomerically pure vicinal diamine platinum complexes, with DNA in solution. It also provides a new kind of chiral recognition, between an enantiomerically pure metal complex and the DNA double helix.

About this Structure

1IHH is a Protein complex structure of sequences from [1] with PT, BA and DNH as ligands. Full crystallographic information is available from OCA.

Reference

2.4 A crystal structure of an oxaliplatin 1,2-d(GpG) intrastrand cross-link in a DNA dodecamer duplex., Spingler B, Whittington DA, Lippard SJ, Inorg Chem. 2001 Oct 22;40(22):5596-602. PMID:11599959

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