Unwinding of zinc finger domain of DNA polymerase I by cis-diamminedichloroplatinum(II).

Abstract:

Structures of a Zn-peptide containing 35 residues (WLQCDDSTCGIVTRQVSVFGKRCLNDGCTGVMRYK) with four cysteines were studied by NMR, CD, and fluorescence spectroscopy, and their structural perturbations and kinetics upon reaction with cis-diamminedichloroplatinum(II) were followed. The secondary structures of the Zn-peptide are comprised of a highly distorted alpha-helix, beta-turn, and an antiparallel beta-sheet. The antiparallel beta-sheet is located at the C-terminus, while the severely distorted alpha-helix is at the N-terminus. The reaction of Zn-peptide with cisplatin revealed severe structural perturbations due to successive coordination with all four cysteine residues. The primary reaction proceeded with the formation of two intermediates. Spectroscopic properties and the rate constant (2.2 +/- 0.3 M(-1) s(-1)) for the formation of the first intermediate support its composition as a Pt-Zn-peptide precursor adduct, held together by hydrogen bonds and comprising a conformationally relaxed peptide due to the unwinding of N-terminus. Subsequently, the precursor adduct undergoes two consecutive aquation processes (k(2) = 3.3 +/- 0. 4 x 10(-4) s(-1) and k(3) = 3.0 +/- 0.3 x 10(-4) s(-1)) to form a second intermediate due to the coordination to a cysteine residue and then to the formation of a bis-cysteine platinum complex. Finally, a secondary product is formed through a slow reaction due to the dissociation of zinc from the peptide and deligation of coordinated ammonia from the platinum atom to form a Pt-peptide complex.

Polymerases:

Topics:

Status:

new topics/pols set partial results complete validated

Results:

No results available for this paper.

Entry validated by:

Log in to edit reference All References

Using Polbase tables:

Sorting:

Tables may be sorted by clicking on any of the column titles. A second click reverses the sort order. <Ctrl> + click on the column titles to sort by more than one column (e.g. family then name).

Filtering:

It is also possible to filter the table by typing into the search box above the table. This will instantly hide lines from the table that do not contain your search text.