Effect of methyl branching of C8H18 alkanes and water activity on lipase-catalyzed enantioselective esterification of ibuprofen

The purpose of this research was to study the effect of the methyl branching of a high log P alkane solvent and the water activity in the organic medium on the initial rate and the enantioselectivity of ibuprofen esterification catalyzed by Candida rugosa lipase. Resolution of ibuprofen is important because S-(+)-ibuprofen has the desired pharmacological activity, whereas the R-(-)-enantiomer causes much of the side effects. The Candida rugosa lipase-catalyzed reaction in isooctane at 40\ub0C and 0.73 water activity gave the best results, both in terms of the initial reaction rate and the enantioselectivity of the reaction. An increase in water activity allowed a higher reaction rate and enantiomeric excess in each of the four solvents. An increase in methyl branching did not necessarily increase the initial reaction rate, but it allowed a higher enantioselectivity, evidenced by an increase in the substrate enantiomeric excess

Effect of methyl branching of C8H18 alkanes and water activity on lipase-catalyzed enantioselective esterification of ibuprofen

The purpose of this research was to study the effect of the methyl branching of a high log P alkane solvent and the water activity in the organic medium on the initial rate and the enantioselectivity of ibuprofen esterification catalyzed by Candida rugosa lipase. Resolution of ibuprofen is important because S-(+)-ibuprofen has the desired pharmacological activity, whereas the R-(-)-enantiomer causes much of the side effects. The Candida rugosa lipase-catalyzed reaction in isooctane at 40°C and 0.73 water activity gave the best results, both in terms of the initial reaction rate and the enantioselectivity of the reaction. An increase in water activity allowed a higher reaction rate and enantiomeric excess in each of the four solvents. An increase in methyl branching did not necessarily increase the initial reaction rate, but it allowed a higher enantioselectivity, evidenced by an increase in the substrate enantiomeric excess

E-Marketplaces: Architecture, Trading Models, and Their Role in Bandwidth Markets

With the Internet providing a powerful low cost medium for businesses to advertise and communicate information about their product and service offers, there is tremendous opportunity for intermediaries to help create efficient markets for businesses to conduct commerce smoothly and securely over the Internet, and in the process derive profit. Among these intermediaries, the role of Electronic Marketplaces is becoming far more important than ever to bring together buyers, sellers and others to facilitate commerce transactions. We envision that different flavors of E-Marketplaces will evolve in the coming years, some community based, some profit based and some created by cooperating firms or businesses. In this paper, we consider the role of profit oriented E-marketplaces. In particular we consider a specific E-Marketplace for computational resources such as bandwidth, and we draw some insights into the architectural requirements and objectives of such intermediaries. In our ..