xylose isomerase

Contains two divalent metal ions, preferably magnesium, located at different metal-binding sites within the active site. The enzyme catalyses the interconversion of aldose and ketose sugars with broad substrate specificity. The enzyme binds the closed form of its sugar substrate (in the case of glucose, only the α anomer) and catalyses ring opening to generate a form of open-chain conformation that is coordinated to one of the metal sites. Isomerization proceeds via a hydride-shift mechanism. Reaction: D-xylopyranose = D-xylulose