title: Purification and characterization of a highly thermostable glucose isomerase produced by the extremely thermophilic eubacterium, Thermotoga maritima.
abstract: Thermotoga maritima, among the most thermophilic eubacteria currently known, produces glucose isomerase when grow in the presence of xylose. The purified enzyme is a homotetramer with submit molecular Wight of about 45,000. It has a number of features in common with previously described glucose isomerases-pH optimum of 6.5 to 7.5, presence of active-site histidine, requirement for metal cations such as Co(2+) and Mg(2+), and preference for xylose as substrate. In addition, it has significant sequence/structural homology with other glucose isomerases, as shown by both N-terminal sequencing and immunological crossreactivity. The T. maritima enzyme is distinguished by its extreme thermostability-a temperature optimum of 105 to 110 degrees C, and an estimated half-life of 10 minutes at 120 degrees C, pH 7.0. The high degree of thermostability, coupled with a neutral to slightly acid pH optimum, reveal this enzyme to be a promising candidate for improvement of the industrial glucose isomerization process.
authors.affiliation: Department of chemical Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: S H
authors.initials: SH
authors.lastname: Brown
authors.forename: C
authors.initials: C
authors.lastname: Sjøholm
authors.forename: R M
authors.initials: RM
authors.lastname: Kelly