“School of Physics”
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| Paper IPM / P / 12124 |
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| Abstract: | |||||||||||||||
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The stability of enzymes with no reduction in their catalytic activity still remains a critical issue in industrial
applications. Naturally occurring osmolytes are commonly used as protein stabilizers. In this study
we have investigated the effects of sorbitol and trehalose on the structural stability and activity of Pseudomonas
cepacia lipase (PCL), using UV?visible, circular dichroism (CD) and fluorescence spectroscopy.
Surface plasmon resonance (SPR) technique was used to trace changes in the refractive index and dielectric
constant of the environment. The results revealed that catalytic activity and intrinsic fluorescence
intensity of PCL increased in the presence of both osmolytes. Far-UV CD spectra indicated that the protein
has undergone some conformational changes upon interacting with these osmolytes. Increasing the
concentration of sorbitol led to changes in the refractive index and consequently the dielectric constant
of environment; whereas in the case of trehalose, such changes were not significant. Unfavorable interactions
of trehalose with protein surface induced higher preferential exclusion from the enzyme?water
interface than that of sorbitol. Results of this report could give further insights about the stabilization
mechanism of osmolytes.
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