Inhibition of lipase from rice (Oryza sativa) by diethyl-p-nitrophenyl phosphate

Raghavendra, M. P. and Ramesh Kumar, Parigi and Prakash, V. (2008) Inhibition of lipase from rice (Oryza sativa) by diethyl-p-nitrophenyl phosphate. European Food Research and Technology, 227. pp. 277-285.

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Abstract

Abstract The inhibition of rice bran lipase (RBL) by diethyl-p-nitrophenyl phosphate was studied with reference to kinetics, nature of inhibition and also elucidate the effect of the inhibitor on the structure—function of the enzyme. Enzyme activity measurements shows that the inhibitor is more effective at 0.050 mM concentration of diethyl-pnitrophenyl phosphate and the activity is 50% at this level of inhibitor concentration. The affinity of substrate for the enzyme was observed by the increase in the velocity of the reaction with increase in the substrate concentrations and double reciprocal plot indicates that the inhibition followed a competitive in nature and inhibition constant Ki is found to be 0.016 mM at pH 7.0. The decrease in apparent thermal denaturation temperature to 4 �C compared to control indicates the destabilization of enzyme in the presence of inhibitor. Fluorescence spectral measurements suggests that pronounced quenching of fluorescence intensity of RBL occurs at higher concentrations of diethylp- nitrophenyl phosphate and ‘Ka’ value was found to be 2.4 · 104 M–1 with free energy change DGo—26 kJ/mol at 30 �C suggesting strong binding between the enzyme and the inhibitor with microenvironmental changes occur at the active site or in the neighbourhood of active site. The far UV-CD data suggest that there is no significant changes in the conformation of the enzyme as a result of binding of diethyl-p-nitrophenyl phosphate. These results indicate that diethyl-p-nitrophenyl phosphate is a inhibitor of RBL and binds to the enzyme in brining about inhibition without any structural alterations.

Item Type:	Article
Uncontrolled Keywords:	Rice bran lipase � Inhibition � Activity � Diethyl-p-nitrophenyl phosphate � Thermal denaturation temperature � Conformational stability
Subjects:	600 Technology > 08 Food technology > 21 Cereals > 01 Rice 600 Technology > 08 Food technology > 16 Nutritive value > 05 Enzymes
Divisions:	Protein Chemistry and Technology
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	09 Aug 2008 10:47
Last Modified:	28 Dec 2011 10:04
URI:	http://ir.cftri.res.in/id/eprint/8681

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