Sunday, August 1, 2010
Pacific Concourse (Hyatt Regency San Francisco)
The gene (axe), encoding an acetylxylan esterase from Thermobifida fusca NTU22, was cloned, sequenced and expressed in Escherichia coli. The gene consists of 786 base pairs and encodes a protein of 262 amino acids. The base composition of the axe coding sequence is 67% G+C and the protein has a predicted pI value of 6.55. The deduced amino acid sequence of the axe esterase exhibited a high degree of similarity with BTA-hydrolase from Thermobifida fusca YX, esterase from Thermobifida alba and lipase from Streptomyces albus. The purified enzyme could be detected as a single band of about 28 kDa by SDS-polyacrylamide gel electrophoresis and this agrees with the predicted size based on the nucleotide sequence. The optimal pH and temperature of the purified esterase were 7.5 and 60°C, respectively. The properties of purified esterase from the E. coli transformant are similar to that of an acetylxylan esterase purified from the original T. fusca NTU22.