The effect of mutations near the T1 copper site on the biochemical characteristics of the small laccase from Streptomyces coelicolor A3(2) (original) (raw)

2015, Enzyme and microbial technology

Bacterial laccases show low activities but can be of biotechnological interest due to industrially suitable characteristics such as thermostability and tolerance to alkaline pH. In this study, three separate mutations (M298F, V290N and V290A) were introduced at or near the T1 copper site of the small laccase (SLAC) from Streptomyces coelicolor A3(2) and biochemical properties were assessed in comparison with the native enzyme. The mutation, V290N showed approximately double the activity of SLAC when ABTS was used as substrate while the specific activity of SLAC-M298F was 4-5 times higher than that of SLAC when the assays were performed at ≥70°C. There was no significant difference in activity with 2,6-dimethoxyphenol (2,6-DMP); however, there was a significant shift in the optimal pH from pH 9.5 (SLAC) to 7.5 (SLAC-V290N). Optimal temperature for activity was not significantly altered but thermostability was reduced in all three mutants. The substrate range of the mutant variants re...