Improvement of enzymatic properties of Rhizopus oryzae α-amylase by site-saturation mutagenesis of histidine 286.

•The His286 residue involved in the catalytic performance of fungal α-amylase was proposed for the first time.•The mutant H286I showed a 1.5–fold increase in half-life at 55 °C and the mutant H286E showed a 6.43–fold increase in half-life at a pH of 4.5.•The maltose-forming ability on soluble starch for mutants H268 L and H286 M was significantly improved.