The intrinsic fluorescence of the enzyme rhodanese (EC 126.96.36.199) 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 language||English (US)|
|Number of pages||7|
|Journal||Biochemical and Biophysical Research Communications|
|State||Published - Nov 17 1975|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology