Purification and characterization of a thermostable class II fumarase from Thermus thermophilus.
A thermostable fumarase was purified from a strain of Thermus thermophilus isolated from a Japanese hot spring. The maximum specific activity of the purified enzyme was 1740 units/mg at pH 8.0 and 85 degreesC. The enzyme was composed of four identical subunits with a molecular weight of 46,000 and displayed other enzymatic characteristics which are common to the class II fumarases. The thermal stability of the purified enzyme was remarkable, with over 80% of the activity remaining after a 24-h incubation at 90 degreesC. The enzyme was also resistant to chemical denaturants; 50% of the initial specific activity was detected in assay mixtures containing 0.8 M guanidine hydrochloride. The purified enzyme shared an extremely high sequence homology with Thermus aquaticus fumarase and Bacillus subtilis fumarase in the first 43 amino acid residues.
Mizobata
T
T
Faculty of Engineering, Tottori University, Tottori, 680-8552, Japan.
Fujioka
T
T
Yamasaki
F
F
Hidaka
M
M
Nagai
J
J
Kawata
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D004795:Enzyme Stability; D005649:Fumarate Hydratase / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D016963:Thermus thermophilus / Q000201:enzymology* / Q000235:genetics
D005649:Fumarate Hydratase