Tryptophan fluorescence intensity and anisotropy decays of human serum albumin resulting from one-photon and two-photon excitation

Joseph R. Lakowicz, Ignacy Gryczynski

Research output: Contribution to journalArticle

78 Scopus citations

Abstract

We measured the emission spectra, intensity decays and anisotropy decays of the single tryptophan residue of human serum albumin (HSA) resulting from one-photon (295-298 nm) and two-photon (590-596) excitation. The emission spectra and intensity decays were independent of the mode of excitation. The anisotropy decays were superficially similar for one- and two-photon excitation. However, upon consideration of the different orientation photoselection for one- and two-photon excitation, the anisotropy data reveal different angles between the absorption and emission oscillators for one-photon and two-photon excitation. This result suggests different relative one-photon and two-photon cross-sections for the 1La and 1Lb transitions of the indole residue. This first report of the time-resolved anisotropy decay of a protein resulting from two-photon excitation suggests that such measurement will yield insights into the complex photophysical properties of tryptophan residues in proteins.

Original languageEnglish
Pages (from-to)1-6
Number of pages6
JournalBiophysical Chemistry
Volume45
Issue number1
DOIs
StatePublished - Nov 1992

Keywords

  • Human serum albumin
  • One- and two-photon excitation
  • Tryptophan anisotropy decay
  • Tryptophan fluorescence intensity decay

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