Xerophytic <Emphasis Type="Italic">Cereus pterogonus</Emphasis> xylose isomerase is a thermostable enzyme

A thermostable xylose isomerase (D-xylose ketol-isomerase; EC.5.3.1.5) was isolated from the cladodes of xerophytic Cereus pterogonus. The enzyme was purified to homogeneity. SDS-PAGE analysis estimated the molecular mass of the enzyme protein at 66 kDa. The enzyme exhibited temperature optima at 60 and 80°C. Though the enzyme activity was optimum at pH 7.0, the enzyme was found to be stable in both acidic and basic pH ranges in the presence of divalent ions Mn²⁺, Co²⁺, and Mg²⁺. This enzyme may find potential use in the food and beverage industry. Published in Khimiya Prirodnykh Soedinenii, No. 2, pp. 169–170, March–April, 2008.