Abstract

The zinc in the metal-binding core of the DNA-binding domain of the nucleotide excision repair protein XPA (M98-F219) can be replaced with cadmium (II) and cobalt (II). Here, we summarize extended X­ ray fine structure spectra collected on each protein in the lyophilized state and in 15% frozen aqueous glycerol solution. Under both conditions the Zn2•, Cd2+,and Co2• are tetrahedrally coordinated to the sulfur atom of four cysteine residues with the Zn-S and Co-S bond lengths nearly identical, at 2.34 A, and the Cd-S bond length at 2.54A.