Figure 6.

Response of wild type and doubly-substituted A. macleodii hydrogenase to various environmental conditions. Thermotolerance was measured as hydrogen evolution activity after denaturation at 85°C for 1 hour. Sensitivity to oxygen was measured by relative H-D exchange rate in the presence of 1% oxygen. Results are expressed as the ratio of activity remaining in the treated samples relative to the untreated controls, and plotted on a log scale over one decade. Error bars represent one geometric standard error of the geometric mean.