Effects of Acetone on NAGase Activity Extracted from Tenebrio molitor Linnaeue

The effects of acetone on activity of N-acetyl-β-D-glucosaminidase (NAGase) from Tenebrio molitor Linnaeus were investigated. The results showed that the remaining enzyme activity rapidly declines with increasing of acetone concentrations. The enzyme activity remained 5% while acetone concentration(V/V) reached 40%, which suggested the acetone makes the enzyme inactivate obviously. Acetone concentration leading to 50% activity lost (repress half- life, IC50) is estimated to be 7.2%. The inactivation of enzyme by lower concentration of acetone (10%) is a reversible reaction with remaining enzyme activity. Thekinetics analysis of inactivation showed that the inactivation of the enzyme in acetone solutions is of mix-competitive type. The combinative constants (KI and KIS) of the free enzyme and the enzyme-substrate complex are determined to be 5.32% and 27.2%, respectively. The value of KIS is larger than that of KI, indicating a marked protective effect of the substrate on the inactivation of the enzyme.