Different effects of microwave energy and conventional heat on the activity of a thermophilic beta-galactosidase from Bacillus acidocaldarius.
The effect of microwave (f = 10.4 GHz) irradiation on a thermostable enzyme was experimentally tested, showing that irreversible inactivation is obtained. Enzymatic solutions (500 microliters, with concentrations between 10-100 micrograms/ml) were exposed at 70 degrees C, at SAR levels of 1.1 and 1.7 W/g for 15, 30, 45, or 60 min, and their activity was compared to that of a sample heated in a water bath at the same temperature. The residual activity of the exposed samples depends on enzyme concentration, microwave power level, and exposure time; activity was reduced to 10% in 10 micrograms/ml solutions treated at 1.7 W/g for 60 min. Microwave effects disappeared at concentrations above 50 micrograms/ml. These results were not found following water bath heating at the same temperature and durations.
La Cara
F
F
Istituto di Biochimica delle Proteine ed Enzimologia, C.N.R., Naples, Italy.
Scarfi
M R
MR
D'Auria
S
S
Massa
R
R
d'Ambrosio
G
G
Franceschetti
G
G
Rossi
M
M
De Rosa
M
M
D001407:Bacillus / Q000201:enzymology; D004795:Enzyme Stability; D006358:Hot Temperature; D008872:Microwaves; D001616:beta-Galactosidase / Q000037:antagonists & inhibitors*
D001616:beta-Galactosidase