xylose isomerase | |||||||||
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D-Xylose isomerase tetramer from Streptomyces rubiginosus PDB 2glk. One monomer is coloured by secondary structure to highlight the TIM barrel architecture.
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Identifiers | |||||||||
EC number | 5.3.1.5 | ||||||||
CAS number | 9023-82-9 | ||||||||
Databases | |||||||||
IntEnz | IntEnz view | ||||||||
BRENDA | BRENDA entry | ||||||||
ExPASy | NiceZyme view | ||||||||
KEGG | KEGG entry | ||||||||
MetaCyc | metabolic pathway | ||||||||
PRIAM | profile | ||||||||
PDB structures | RCSB PDB PDBe PDBsum | ||||||||
Gene Ontology | AmiGO / QuickGO | ||||||||
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Search | |
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PMC | articles |
PubMed | articles |
NCBI | proteins |
In enzymology, a xylose isomerase (EC 5.3.1.5) is an enzyme that catalyzes the interconversion of D-xylose and D-xylulose. This enzyme belongs to the family of isomerases, specifically those intramolecular oxidoreductases interconverting aldoses and ketoses. The isomerase has now been observed in nearly a hundred species of bacteria. Xylose-isomerases are also commonly called fructose-isomerases due to their ability to interconvert glucose and fructose. The systematic name of this enzyme class is D-xylose aldose-ketose-isomerase. Other names in common use include D-xylose isomerase, D-xylose ketoisomerase, and D-xylose ketol-isomerase.
The activity of D-xylose isomerase was first observed by Mitsuhashi and Lampen in 1953 in the bacterium Lactobacillus pentosus. Artificial production through transformed E.coli have also been successful. In 1957, the D-xylose isomerase activity on D-glucose conversion to D-fructose was noted by Kooi and Marshall. It is now known that isomerases have broad substrate specificity. Most pentoses and some hexoses are all substrates for D-xylose isomerase. Some examples include: D-ribose, L-arabinose, L-rhanmose, and D-allose.
Conversion of glucose to fructose by xylose isomerase was first patented in the 1960s, however, the process was not industrially viable as the enzymes were suspended in solution, and recycling the enzyme was problematic. An immobile xylose isomerase that was fixed on a solid surface was first developed in Japan by Takanashi. These developments were essential to the development of industrial fermentation processes used in manufacturing high fructose corn syrup.