Binding of alkyl 1-thio-beta-D-galactopyranosides to beta-D-galactosidase from E. coli.
The binding of a series of alkyl 1-thio-beta-D-galactopyranosides to beta-D-galactosidase from E. coli has been investigated. The inhibition constants were compared to the partition coefficients for the transfer of these substrate-analogues from water to 1-octanol. The relationships between the observed binding-constants and the partition coefficients indicate that part of the aglycon group binds to a hydrophobic area that is limited in relation to the length of hydrocarbon chain that can be accomodated. Outside this area, the hydrocarbon chain is only partially desolvated. The main driving-force  for binding of the aglycon group is the increase in entropy resulting from the return of water molecules from the more-organized layer around the solute molecule to the bulk-water phase.
D004926:Escherichia coli / Q000201:enzymology*; D005696:Galactosidases / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008433:Mathematics; D011485:Protein Binding; D013329:Structure-Activity Relationship; D013696:Temperature; D013862:Thiogalactosides; D013865:Thioglycosides
D013862:Thiogalactosides; D013865:Thioglycosides; D005696:Galactosidases