Monday, May 5, 2008
6-49

Influence of Formic Acid in a Pre-Purified Xylose Reductase Aiming anEnzymatic NAD(P)H Regeneration System

R.F. Branco, J.C. Santos, B.F. Sarrouh, and Sílvio Silva Sr.. BIOTECHNOLOGY DEPARTMENTq, University of São Paulo - Engineer School of Lorena, Estrada Municipal do Campinho, Lorena, Brazil

Oxireductive enzymes are playing an important role in the current biotechnology and organic chemistry, since they are capable to reduce or oxidize different types of compounds, which could result in a less costly process than a chemical way. NAD(P)H-dependent D-Xylose reductase (XR) belongs to the monomeric aldo–keto reductase superfamily. This enzyme catalyzes the reaction of xylose to xylitol, with aid of the co-enzyme NAD(P)H. The XR gene is used to construct recombinant S. cerevisiae strain for utilizing xylose and producing ethanol; it can be used, also, for xylitol production and in other process that needs an enzymatic NAD(P)H regeneration system (ENRS). However, there are not many studies of the influence of different substances in the XR kinetic, although these studies are very important to better understand the behavior of this enzyme in different reactional media. In this context, the present work had as objective to determinate the formic acid (a hypothetical ENRS in XR catalyzed reactions) influence in the pre-purified NADPH-dependent XR from Candida guilliermondii. The enzymatic extract produced by the cultivation of the yeast cells and was pre-purified by the reversed micelles technique. The enzymatic assays were performed at 30°C using a constant concentration of NADPH and formic acid, only varying the concentration of xylose. The results showed that formic acid has an uncompetitive inhibitory effect under XR, the apparent inhibition constant was 0.14±0.1 M. This result showed that acid formic is a good alternative for an ENRS in XR catalyzed reactions. Acknowledgements: FAPESP, CNPq and CAPES.

See more of Poster Session Two
See more of General Submissions

See more of The 30th Symposium on Biotechnology for Fuels and Chemicals (May 4 -- 7, 2008)