Fig. 1.

Assessment of thermostability for wild-type GST-GCK and mutant GST-GCK(p.Ile19Asn) proteins. Enzyme solutions were diluted to 250 mg/L as described in Galán et al. (2006). (a) The enzyme solution was incubated for 30 min at different temperatures ranging from 30 to 55°C and then assayed at 30°C as described in Methods. (b) The enzyme solution was incubated for different periods of time from 5 to 60 min at 50°C. After incubation, GCK activity was assayed at a glucose concentration of 100 mmol/L. Means and SD of six independent experiments (n = 6), from three enzyme preparations, are shown. (*) p < 0.005, Student’s t-test with Levene’s test for equality of variances. (**) p < 0.005, non-parametric Mann–Whitney U test