TAUROCHOLATE-INDUCED DIMERIZATION OF BOVINE CHOLESTEROL ESTERASE IN SODIUM DODECYL-SULFATE

Purified bovine cholesterol esterase (CE) showed one major band with a n apparent molecular mass of 58 kDa on sodium dodecyl sulfate-polyacry lamide gel electrophoresis (SDS-PAGE). In the presence of taurocholate another major band with an apparent molecular mass of 116 kDa, corres ponding to the dimer, appeared. Longer heating times and higher concen trations of CE in SDS-sample buffer increased the relative amount of t he dimer. Higher SDS concentration in the sample buffer reduced the am ount of dimer. Mercaptoethanol concentration had no effect. The dimer did not contain taurocholate and readily reverted to the monomer. It i s concluded that taurocholate mediates the dimerization of CE in SDS b y facilitating the formation of hydrophobic interactions between monom eric subunits. (C) 1997 Elsevier Science B.V.