Further kinetic and molecular characterization of an extremely heat-stable carboxylesterase from the thermoacidophilic archaebacterium Sulfolobus acidocaldarius.
The carboxylesterase (serine esterase, EC 3.1.1.1) from Sulfolobus acidocaldarius was purified 940-fold to homogeneity by an improved purification procedure with a yield of 57%. In the presence of alcohols the enzyme catalyses the transfer of the substrate acyl group to alcohols in parallel to hydrolysis. The results show the existence of an alcohol-binding site and a competitive partitioning of the acyl-enzyme intermediate between water and alcohols. Aniline acts also as a nucleophilic acceptor for the acyl group. On the basis of titration with diethyl p-nitrophenyl phosphate, a number of four active centres is determined for the tetrameric carboxylesterase. The sequence of 20 amino acid residues at the esterase N-terminus and the amino acid composition are reported.
Sobek
H
H
Institut für Mikrobiologie der Universität Hohenheim, Stuttgart, Federal Republic of Germany.
Görisch
H
H
D000595:Amino Acid Sequence; D001105:Archaea / Q000201:enzymology*; D001419:Bacteria / Q000201:enzymology*; D002384:Catalysis; D004950:Esterases / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data
D004950:Esterases; C022635:serine esterase