Abstract
Abstract Fluorescence studies of crystalline bovine liver rhodanese indicate that the reactive sulfhydryl group is in a region which can participate in hydrophobic (apolar) interactions. Fluorescence polarization studies confirm that rhodanese exists in a mobile monomer-dimer equilibrium. Experiments with hydrophobic probing reagents indicate that the appearance of hydrophobic regions is correlated with the dissociation of dimers to monomers.
Highlights
Fluorescence studies of crystalline bovine liver rhodanese indicate that the reactive sulfhydryl group is in a region which can participate in hydrophobic interactions
The appearance of a stable dimer in rhodanese preparations exposed to air, as well as pH activity data, led to the suggestion that repulsion of sulfhydryl groups lying close together in the reversible dimer causes dissociation to monomers by ionic repulsion
A variety of approaches led to the conclusion that 1 of the 4 tryptophanyl residues of the rhodanese monomer is at the active site and is in close proximity to the implicated sulfhydryl group [6,7,8]
Summary
Fluorescence studies of crystalline bovine liver rhodanese indicate that the reactive sulfhydryl group is in a region which can participate in hydrophobic (apolar) interactions. Fluorescence polarization studies confkm that rhodanese exists in a mobile monomer-dimer equilibrium. Experiments with hydrophobic probing reagents indicate that the appearance of hydrophobic regions is correlated with the dissociation of dimers to monomers. The appearance of a stable dimer in rhodanese preparations exposed to air, as well as pH activity data, led to the suggestion that repulsion of sulfhydryl groups lying close together in the reversible dimer causes dissociation to monomers by ionic repulsion [5, 6]. The work reported here indicates that the active site sulfhydryl group behaves as if it were in a region which can participate in apolar interactions. The evidence suggests that interactions involving this hydrophobic region are important in maintaining the dimeric structure of rhodanese
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