The bifunctional pyruvate decarboxylase/pyruvate ferredoxin oxidoreductase from Thermococcus guaymasensis
Document Type
Article
Publication Title
Archaea
Publication Date
1-1-2014
Abstract
The hyperthermophilic archaeon Thermococcus guaymasensis produces 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. guaymasensis under 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-1 and 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. © 2014 Mohammad S. Eram et al.
Volume
2014
DOI
10.1155/2014/349379
Recommended Citation
Eram, M., Oduaran, E., & Ma, K. (2014). The bifunctional pyruvate decarboxylase/pyruvate ferredoxin oxidoreductase from Thermococcus guaymasensis. Archaea, 2014 https://doi.org/10.1155/2014/349379
ISSN
14723646