| Autor: |
McDonough R; Institute for Nanoscale Science and Technology, School of Chemical and Physical Sciences, Flinders University, Bedford Park, SA 5042, Australia., Williams CC; CSIRO Manufacturing, Clayton, Melbourne, VIC 3168, Australia., Hartley CJ; CSIRO Environment, Black Mountain, ACT 2601, Australia., French N; CSIRO Environment, Black Mountain, ACT 2601, Australia., Scott C; CSIRO Environment, Black Mountain, ACT 2601, Australia., Lewis DA; Institute for Nanoscale Science and Technology, School of Chemical and Physical Sciences, Flinders University, Bedford Park, SA 5042, Australia. |
| Abstrakt: |
Understanding the mechanism of interfacial enzyme kinetics is critical to the development of synthetic biological systems for the production of value-added chemicals. Here, the interfacial kinetics of the catalysis of β-nicotinamide adenine dinucleotide (NAD + )-dependent enzymes acting on NAD + tethered to the surface of silica nanoparticles (SiNPs) has been investigated using two complementary and supporting kinetic approaches: enzyme excess and reactant (NAD + ) excess. Kinetic models developed for these two approaches characterize several critical reaction steps including reversible enzyme adsorption, complexation, decomplexation, and catalysis of the surface-bound enzyme/NAD + complex. The analysis reveals a concentrating effect resulting in a very high local concentration of enzyme and cofactor on the particle surface, in which the enzyme is saturated by surface-bound NAD, facilitating a rate enhancement of enzyme/NAD + complexation and catalysis. This resulted in high enzyme efficiency within the tethered NAD + system compared to that of the free enzyme/NAD + system, which increases with decreasing enzyme concentration. The role of enzyme adsorption onto solid substrates with a tethered catalyst (such as NAD + ) has potential for creating highly efficient flow biocatalytic systems. |
