Asparagine and glutamine deamidation kinetics. WT l-ASP or Q59L l-ASP was added to a reaction solution containing 100 µM asparagine, 1600 µM glutamine, or both. Concentrations of asparagine (A) and glutamic acid (B) were measured over a 1500-s time series by LC-MS/MS. Solid symbols represent concentrations in the single substrate reaction, and open symbols represent concentrations in the mixture.