DNA polymerase β reveals enhanced stability in reverse microemulsions

Water is essential for the stability and functions of proteins and DNA. Reverse microemulsions are model systems where the structure and dynamics of water are controlled. We have investigated the different hydration and confinement effects on the activity and the stability of mammalian DNA polymerase β in the complex reverse microemulsions, containing ionic and nonionic surfactants in decane/hexanol. The enzyme displays high processivity on primed single-stranded M13mp19 DNA with maximal activity at 10% of water content. DNA polymerase reveals the enhanced stability toward the thermal and the chemical denaturation. The enzyme is still active at 65 °C and in 4 M urea. The data provide direct evidence for strong influence of microenvironment on DNA polymerase activity and stability.