Fig. 1
From: When substrate inhibits and inhibitor activates: implications of β-glucosidases
Nonproductive binding of substrate. a When a BG containing three consecutive binding subsites, one glycone-binding subsite (−1) and two aglycone-binding subsites (+1 and +2) are studied with a dimeric substrate (like pNPG), the substrate can combine with the enzyme both productively (ES complex) and nonproductively (ES(np) complex). The position of the scissile bond is shown with the arrow. b Michaelis–Menten equation parameters derived for the mechanism in panel a using the steady-state treatment. k ES is the lumped catalytic rate constant for the formation of both products. The superscript exp refers to the expected value K m would have if no nonproductive complexes were formed. K s and K s(np) are the true equilibrium dissociation constants of productive and nonproductive enzyme-substrate complexes, respectively