The activity and conformation changes of catalase in water - ethanol mixtur
es were measured at 298.15K by means of microcalorimetry and fluorescence s
pectroscopy. The results showed that the Michaelis constant K-m of catalase
catalyzed reaction as well as the relative fluorescence intensity of catal
ase increased the rate constant k(2) and the activity of catalase decreased
with increasing the ethanol concentration. The conformation of catalase wa
s changed with losing activity at the various concentration of ethanol. The
lose of activity of catalase in water - ethanol mixtures was caused by the
inhibition of ethanol and the conformational change of catalase.