TY - JOUR A2 - Whitman, William B. AU - Eram, Mohammad S. AU - Oduaran, Erica AU - Ma, Kesen PY - 2014 DA - 2014/05/29 TI - The Bifunctional Pyruvate Decarboxylase/Pyruvate Ferredoxin Oxidoreductase fromThermococcus guaymasensisSP - 349379 VL - 2014 AB - The hyperthermophilic archaeon Thermococcus guaymasensisproduces ethanol as a metabolic end product, and an alcohol dehydrogenase (ADH) catalyzing the reduction of acetaldehyde to ethanol has been purified and characterized. However, the enzyme catalyzing the formation of acetaldehyde has not been identified. In this study an enzyme catalyzing the production of acetaldehyde from pyruvate was purified and characterized from T. guaymasensisunder strictly anaerobic conditions. The enzyme had both pyruvate decarboxylase (PDC) and pyruvate ferredoxin oxidoreductase (POR) activities. It was oxygen sensitive, and the optimal temperatures were 85°C and >95°C for the PDC and POR activities, respectively. The purified enzyme had activities of 3.8 ± 0.22  U mg⁻¹and 20.2 ± 1.8  U mg⁻¹, with optimal pH-values of 9.5 and 8.4 for each activity, respectively. Coenzyme A was essential for both activities, although it did not serve as a substrate for the former. Enzyme kinetic parameters were determined separately for each activity. The purified enzyme was a heterotetramer. The sequences of the genes encoding the subunits of the bifunctional PDC/POR were determined. It is predicted that all hyperthermophilic β-keto acids ferredoxin oxidoreductases are bifunctional, catalyzing the activities of nonoxidative and oxidative decarboxylation of the corresponding β-keto acids. SN - 1472-3646 UR - https://doi.org/10.1155/2014/349379 DO - 10.1155/2014/349379 JF - Archaea PB - Hindawi Publishing Corporation KW - ER -