Pharmaceutical Sciences Faculty Publications

Title

Zinc-Induced Conformational Changes in the DNA-Binding Domain of the Vitamin D Receptor Determined by Electrospray Ionization Mass Spectrometry

Document Type

Article

Publication Date

1-1-1998

Journal Title

Journal of the American Society for Mass Spectrometry

ISSN

1044-0305

Volume

9

Issue

1

First Page

8

Last Page

14

DOI

10.1016/S1044-0305(97)00229-8

PubMed ID

9679591

Abstract

Electrospray ionization mass spectrometry (ESI-MS) was used to measure conformational changes within the DNA-binding domain of the vitamin D receptor (VDR DBD) upon binding zinc (Zn2+). As increasing concentrations of Zn2+ were added to the VDR DBD, a gradual shift in the mass envelope to lower charge states was observed in the multiply charged spectrum. The shift in the charge states was correlated to changes observed in the far-ultraviolet circular dichroic (far-UV CD) spectrum of the protein as it was titrated with Zn2+. Both the multiply charged ESI and far-UV CD spectra of the Zn(2+)-titrated protein show that the binding of the first Zn2+ ion to the protein results in very little conformational change in the protein. The binding of a second Zn2+ ion resulted in a significant alteration in the structure of the protein as indicated by changes in both the multiply charged ESI and far-UV CD spectra. Much smaller changes were seen within the multiply charged ESI or far-UV CD spectra upon increasing the Zn2+ concentration beyond 2 mol/mol of protein. The results presented indicate that ESI-MS in combination with CD is a powerful method to measure gross conformational changes induced by the binding of metals to metalloproteins.

Keywords

Circular dichroism, DNA-binding proteins, electrochemistry, mass spectrometry, protein conformation, receptors, calcitriol, spectrophotometry, ultraviolet, zinc

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