Purification and characterization of a highly thermostable glucose isomerase produced by the extremely thermophilic eubacterium, Thermotoga maritima
✍ Scribed by Stephen H. Brown; Carsten Sjøholm; Robert M. Kelly
- Publisher
- John Wiley and Sons
- Year
- 1993
- Tongue
- English
- Weight
- 856 KB
- Volume
- 41
- Category
- Article
- ISSN
- 0006-3592
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✦ Synopsis
Thermotoga maritima, among the most thermophilic eubacteria currently known, produces glucose isomerase when grown in the presence of xylose. The purified enzyme is a homotetramer with subunit molecular weight 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 activesite histidine, requirement for metal cations such as Coz+ and Mg2+, and preference for xylose as substrate. In addition, it has significant sequence/structural homology with other glucose isomerases, as shown by both Nterminal sequencing and immunological crossreactivity. The T. maritima enzyme is distinguished by its extreme thermostability-a temperature optimum of 105 to llO°C, and an estimated half-life of 10 minutes at 120°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.