Contact versus energy transfer fluorescence quenching in the sulfur substituted form of the enzyme rhodanese: A study using cesium ion resolved emission spectra

Kathleen Guido, Paul M. Horowitz

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

The intrinsic fluorescence of the enzyme rhodanese (EC 2.8.1.1) can be resolved into separate contributions from solvent accessible and solvent inaccessible tryptophan residues by comparing spectra run in 2 M NaCl with those run in the quenching solution, 2 M CsCl. Both these classes of tryptophan residues are quenched when sulfur is transferred to rhodanese forming a sulfur substituted enzyme which is an intermediate in the catalytic cycle. This observation is consistent with a non-radiative energy transfer mechanism for quenching as opposed to a mechanism requiring direct contact between the bound sulfur and an active site tryptophan. Therefore, the data supports the hypothesis that the primary stabilizing influence in forming the substituted enzyme intermediate is a persulfide bond between an active site sulfhydryl group and the transferred sulfur.

Original languageEnglish (US)
Pages (from-to)670-676
Number of pages7
JournalBiochemical and Biophysical Research Communications
Volume67
Issue number2
DOIs
StatePublished - Nov 17 1975
Externally publishedYes

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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