SOLID-STATE ENZYME DEACTIVATION IN AIR AND IN ORGANIC-SOLVENTS

Thermal deactivation of solid-state acid phosphatase (E.C. 3.1.3.2, fr om potato) is analyzed, both in the presence and in the absence of org anic solvents. The thermal deactivation profile departs from first ord er kinetics and shows an unusual, temperature-dependent, asymptotic va lue of residual activity. The process is described by a phenomenologic al equation, whose theoretical implications are also discussed. The to tal amount of buffer salts in the enzyme powder dramatically affects e nzyme stability in the range 70 degrees to 105 degrees C. The higher s alt/protein ratio increases the rate of thermal deactivation. The deac tivation rate is virtually unaffected by the presence of organic solve nts, independent of their hydrophilicity. (C) 1994 John Wiley & Sons, Inc.