Detection of enzyme-catalyzed polysaccharide synthesis on surfaces

Abstract

Strategically important cellular components, such as the cell wall and the starch granule, present surfaces during their biosynthesis and degradation. The enzymology of such surfaces is experimentally challenging and goes well beyond classical solution-state analyses. The kinetics of surface catalysis is complex but tractable. A number of approaches to monitor surface catalysis are reviewed and each is suited to a different biological problem. Particular attention is paid to a method we have recently developed for quantitatively monitoring polysaccharide synthesis on a surface in real time using surface plasmon resonance spectroscopy. This method has many attractive features with the potential to tackle both biological and industrial problems.

A generic rate law for surface‐active enzymes

“…Before we embark on the derivation of the rate law for surface‐active enzymes, we will consider adsorption as an isolated process which is essentially completed and, thus, in equilibrium during the phase of catalytic turnover. There is some experimental evidence [31,32] justifying the assumption of such a temporal hierarchy and several studies of interfacial enzyme kinetics used adsorption isotherms [5,33,34], albeit without applying Cha's method.…”

“…Artificial model substrates with well‐defined interfacial properties are arguably a very convenient choice to characterize surface‐active enzymes. For instance, the use of chips with self‐assembled monolayers [8,31,32,58,59] and lipid monolayers [60] allow control over the surface number density of the substrate 〈∗ S 〉. Coupled with techniques like surface‐plasmon resonance spectroscopy they allow for real‐time monitoring of adsorption and catalysis.…”