Deamidation and glycation of a Bacillus licheniformis α-amylase during industrial fermentation can improve detergent wash performance

Abstract The industrial thermostable Bacillus licheniformis α-amylase (BLA) has wide applications, including in household detergents, and efforts to improve its performance are continuously ongoing. BLA during the production is deamidated glycated resulting multiple forms with different isoelectric points. Forty modified positions were identified by tandem mass spectrometric peptide mapping of separated focusing. These 12 asparagine, 9 glutamine, 8 arginine 11 lysine residues mostly situated on enzyme surface several belong regions involved stability, activity carbohydrate binding. Eight presumed interact starch at active site binding sites (SBSs) subjected mutational analysis. Five mutants mimicking deamidation (N→D, Q→E) substrate cleft showed moderate no effect thermostability k cat K M for maltoheptaose amylose. Notably, mutations improved laundry wash efficiency detergents pH 8.5 10.0. Replacing three reducing sugar reactive side chains (K→M, R→L) a distant region two SBSs enhanced especially liquid detergent 8.5, slightly enzymatic maintained thermostability. Wash was most (5-fold) N265D mutant near subsite +3.