Assaying Enzymes from Hyperthermophiles

The determination of kinetic and thermodynamic data from hyperthermophilic enzymes at physiological temperature (i. e. ‡ 80 C) raises a number of technical and fundamental problems. Based on studies of purified enzymes from the model organism Pyrococcus furiosus several of these problems are identified and explored here. It is proposed that kinetic and thermodynamic data on hyperthermophilic enzymes be reported at the organism's growth temperature or, alternatively, at a lower temperature compatible with practical assay conditions with additional data obtained at yet lower temperatures to allow for extrapolation.