Gd3+ vibronic side band spectroscopy. New optical probe of Ca2+ binding sites applied to biological macromolecules

I. E. Iben, M. Stavola, R. B. Macgregor, X. Y. Zhang, J. M. Friedman

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A new spectroscopic technique is presented for obtaining infraredlike spectra of the binding sites of Ca2+ and other metals in biological macromolecules. The technique, based on the Ca(2+)-like binding properties of Gd3+, utilizes vibronic side bands (VSB) that appear in Gd3+ fluorescence. In the fluorescence spectrum of Gd3+, the separation in photon frequency between a VSB and its electronic origin at approximately 32,150 cm-1 (approximately 311 nm) is a direct measure of the vibrational frequency of a ligand coordinated to Gd3+ ion. As a consequence, the VSB are uncomplicated by molecular vibrations distant from the Gd3+ binding site. The vibrational spectra resulting from the VSB of Gd3+ coordinated to a Ca2+ binding protein, a phospholipid, and DNA are presented.

Original languageEnglish (US)
Pages (from-to)1040-1049
Number of pages10
JournalBiophysical journal
Issue number5
Publication statusPublished - Jan 1 1991
Externally publishedYes


ASJC Scopus subject areas

  • Biophysics

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