Monday, August 2, 2010
Pacific Concourse (Hyatt Regency San Francisco)
D-chiro-Inositol, an epimer of 3-hydroxyl group of myo-inositol, is found in significant quantities in buckwheat. D-chiro-Inositol is one of cyclitols, which is involved in cellular osmoregulation of some plant. D-chiro-Inositol has been reported as a mediator of insulin action. It has been also known that it can lower blood pressure, improve glucose disposal in diabetes, and increase frequency of ovulation. D-chiro-Inositol is synthesized from myo-inositol by inositol epimerase. To date, only limited studies on inositol epimerase have been reported. The inositol epimerase was codon-optimized for expression in E. coli, based on amino acid sequence of myo-inositol dehydrogenase of Agrobacterium sp.. Recombinant E. coli BL21 (DE3) strain harboring the synthetic inositol epimerase produced about 0.5 g/L D-chiro-inositol with initial supplementation of 30 g/L myo-inositol. Since E. coli has no inositol transporter, inositol uptake could be limited for higher D-chiro-inositol production in E. coli. Genes encoding myo-Inositol transporters were cloned from Bacillus subtilis and Salmonella typhimurium, which were known as the strains with myo-inositol transporter. Each strain has major and minor transporters which are iolT and iolF in B. subtilis, and iolT1 and iolT2 in S. typhimurium. E. coli harboring iolT1 and iolT2 of S. typhimurium, produced the highest amount of D-chiro-inositol, 4 g/L.
This work was supported by the Ministry of Knowledge Economy in Korea (Grant No. 70006812), Leading Industry Development for Economic Region in Korea (Grant No. 70007704), and the BK21 Program in Korea.