期刊名：European Physical Journal E

題目：Co-ion dependence of DNA nuclease activity suggests hydrophobic cavitation as a potential source of activation energy

作者：H.-K. Kim, E. Tuite, B. Nord′en, and B.W. Ninham

摘要：The source of the activation energy that allows cutting of DNA by restriction enzymes is unclear. A systematic study of the cutting effiffifficiency of the type-II restriction endonuclease EcoRI, with varying background electrolyte ion pair and buffffer reported here, shows only a modest dependence of effiffifficiency on cation type. Surprisingly, effiffifficiency does depend strongly on the presumed indifffferent anion of the background salt. What emerges is that competition between the background salt anion and the buffffer anion for the enzyme and DNA surfaces is crucial. The results are unexpected and counterintuitive from the point of view of conventional electrolyte theory. However, taken together with recent developments in surface chemistry, the results do fall into place and could also suggest a novel mechanism for enzyme activity as an alternative to metal-activated hydrolysis: microscopic cavitation in a hydrophobic pocket might be the source of activation energy.