The intracellular environment in which biological reactions occur is a complex solution, composed of many different microenvironments with differing local concentrations of ions, small molecules, nucleotides, and proteins. These different environments exist in close proximity to one another, and biological reactions have evolved to occur in this heterogeneous media. Here, we report an experimental and mathematical model system using a polyethylene glycol/sodium citrate aqueous two phase system (ATPS) that captured aspects of the intracellular environment. The sequential reaction of glucose oxidase (GOX) and horseradish peroxidase (HRP) occurred in the ATPS. We found that the enzymes and substrates partitioned in the ATPS and different effects from the media on the individual enzyme rates, which resulted in different local concentrations and therefore different rates of reaction in the phases, especially with respect to HRP. Using the kinetic data, we developed a mathematical model that quantitatively described the kinetics of the reaction in the two-phase environment, and we then used the model to predict a case in which the concentration of enzyme was higher. We found that the interface is vital for product formation. These data suggest that relatively complex reactions in heterogeneous reaction media can be described experimentally and mathematically.

Sequential reactions in heterogeneous reaction media: Experiments and modeling for glucose oxidase and horseradish peroxidase in a PEG/citrate aqueous two-phase system

247th National Meeting (2014)

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