The Bifunctional Pyruvate Decarboxylase/Pyruvate Ferredoxin Oxidoreductase from Thermococcus guaymasensis
Figure 2
Oxygen sensitivity and optimal pH for T. guaymasensis PDC and POR activities. The effect of air exposure on (a) POR and (b) PDC reactions was measured at different time points in TgPOR/PDC aliquots exposed to air while stirring. The relative activities of 100% equal the highest measured specific activity at time zero with no exposure to air (16.2 U mg−1 and 2.2 U mg−1 for POR and PDC activities, resp.). The effect of pH on (c) POR and (b) PDC activities of TgPOR/PDC was determined under strictly anaerobic conditions at 80°C. The relative activities of 100% equal the highest measured specific activities (17.4 U mg−1 and 2.6 U mg−1 for POR and PDC, resp.). For the optimal pH determination experiments the filled circles represent the reactions with sodium phosphate buffers (pH 6.2, 7.0, 7.5, and 8.0), the open circles represent the reactions with EPPS buffer (pH 8.0, 8.4, 9.0, and 9.5), the filled triangles represent glycine buffer (pH 9.5 and 10), and open triangles represent the CAPS buffer (pH 10.5 and 11.0).
