99A-30 |
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S.-E. PARK, M.-H. Cho, and C.-S. Park. Department of Food Science and Technology, KyungHee University, 1 Secheon-ri, Kiheung, Yongin, 449-701, South Korea Palatinose (6-O-a-D-glucopyranosyl-D-fructose) is a sucrose isomer with physical and organoleptic properties similar to those of sucrose. Due to its non-cariogenicity and low calorific value it is an ideal sugar substitute for use in food industry. Several microorganisms, such as Erwinia raphontici, Serratia plymuthica, and Klebsiella planticola, have been known to produce palatinose from sucrose. Recent advance in biotechnology leads to the functional expression of sucrose isomerase in E. coli and the efficient production of palatinose form sucrose. Our objective was to express the sucrose isomerase gene from Erwinia raphontici in E. coli and to use the recombinant enzyme to the production of palatinose. The sucrose isomerase gene from Erwinia raphontici was cloned by PCR. The efficient expression and purification of sucrose isomerase gene were succeeded in the use of pHis119, an N-terminally histidine-tagged expression vector. The gene corresponding to sucrose isomerase in Erwinia raphontici was successfully cloned and expressed in E. coli. The recombinant protein was homogeneously purified by Ni-NTA affinity chromatography. The recombinant sucrose isomerase converted sucrose into isomaltulose, trehalulose and trace amounts of glucose and fructose. In addition to the purified sucrose isomerase, the immobilized recombinant E. coli cell could transform more than 80% of sucrose (50% solution) into palatinose with in 4 hr. This result suggested that the palatinose, an ideal sugar substitute, could be efficiently produced by the recombinant sucrose isomerase expressed in E coli. Also the E. coli cell harboring the recombinant enzyme may be utilized as an immobilized form in the production of palatinose.
Session 99A, Biotechnology: General
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