Fingerprinting processive β-amylases

Abstract

Many polysaccharide hydrolases are capable of processive action, where they perform repeated attacks without dissociating from the substrate molecule. In this paper, we extend the “Fingerprinting method”, a method that can be used to determine the relative specificities that an enzyme has for the various reactions that it can catalyze in a multi-step reaction scheme, to reaction schemes involving processive action. We do this for three case studies for the hydrolysis of linear malto-oligosaccharides by β-amylase, an exoenzyme that successively removes maltose units from the non-reducing ends of the molecules. In these case studies, we demonstrate that it is possible to use reaction profiles to determine, simultaneously, the relative specificities that the enzyme has for the different species in the reaction mixture and the probabilities of processive action occurring. These parameters can be used in models for designing and optimizing hydrolysis processes and also to guide protein engineering programs.