Effects of Temperature on the Activity of Congregibacter litoralis KT 71 β -lactamase in the Hydrolysis of 4-nitrophenyl Dodecanoate

Abstract

The effects of temperature on the activities of Congregibacter litoralis KT71 β-lactamase (CLL) was determined by varying the assay temperature from 30°C to 70°C. The enzyme’s residual activity was also determined by incubating the assay mixture which excluded the substrate for one hour at 70°C before addition of the substrate to start the reaction. The enzyme activity was measured using a spectrophotometer at a wavelength of 405 nm. The hydrolysis of 4-nitrophenyl dodecanoate to yield 4-nitrophenol was monitored by reading the absorbance at 25 minutes after the addition of substrate to the pre incubated assay mixture. The assay was done in three replicates. The initial velocity was determined and this was compared with Thermomyces lanuginosus Lipase (TLL) which served as a reference enzyme. Results show that increase in temperature from 30°C to 70°C proportionately decreased the activity of Congregibacter litoralis KT71 β-lactamase. Similarly, Thermomyces Lanuginosus Lipase showed a progressively decreasing activity as the temperature increased within the same range. Results from the assay on the residual activity at 70°C shows that both CLL and TLL has residual activities of 63% and 48% respectively. This suggests that reactions involving these enzymes at 70°C can occur without the enzyme completely inactivated. Results also shows that CLL is more thermally stable than TLL at 70°C. Considering the vast importance of thermally stable lipases and their industrial applications, there is need to study the kinetics of this enzyme to give an understanding of how the enzyme system works. Hence findings from this study is of great significance.