| Comments |
P.1665 left column bottom paragraph: "To investigate the stability of the biocatalyst, the reconstituted lyophilized cells were incubated for several days at 30°C in PBS. The biocatalyst stayed active for at least 5 days and lost about 1% activity per hour. The same characteristics were observed for the purified enzyme (Fig. 5A). The half-life of the biocatalyst was 65.3 h for purified G6PDH and 70.6 h for the surface-displayed enzyme (Table II). The expected lifetime productivity of a biocatalyst can be assessed by its total turnover number (TTN), a dimensionless number expressing product yield in relation to the amount of biocatalyst." P.1665 right column top paragraph: "A TTN in the magnitude of 10^7 was obtained (Table II) for both, the purified and displayed G6PDH, which represent a theoretical maximum, as saturating substrate conditions are very rarely reached in industrial processes. Under reaction conditions, substrate and product inhibition as well as NADPH degradation would result in lower TTNs. The calculated TTNs are in the range of industrial grade dehydrogenases (Rogers and Bommarius, 2010) and underline the applicability of the whole cell biocatalyst for NADPH regeneration." |