Resolution of R/S-α-Hydroxy Fatty Acids by Immobilized Lipase on Rice Hull Ash

Abstract

Rice hull ash obtained from rice hull which was heated for 2 hrs, at 500 ^oC was treated with10% sulfuric acid. The ash was used as a support for immobilization of Candida rugosa lipase. Theimmobilized lipase can resolve R/S-α-hydroxy octanoic acid menthyl esters in iso-octane with a smallamount of ter- butanol as a co-solvent for the substrate. The solvent composition strongly affects theenzyme selectivity as well as the product yield. The highest yield is obtained from system with tertbutanolis the co-solvent, when it compares to other cosolvents, such as Diisopropylether, Di-nbutylether,Trichloroethylene and Tetrachloroethylene. However, higher concentrations of co-solventstend to decrease the product yields. Water content and substrate concentration strongly affect theenzyme selectivity. The optimal condition for highest enantiomeric excess is 0.6% water and thealcohol to α-hydroxy fatty acid ratio is 7.5.

Keywords : α-Hydroxy Fatty Acid / Rice Hull Ash / Immobilized Enzyme / EnaneiomericExcess