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Preferential interaction of denaturants with rice bran lipase

Rajeshwara, A. N. and Gopalakrishna, K. N. and Prakash, V. (1996) Preferential interaction of denaturants with rice bran lipase. International Journal of Biological Macromolecules, 19. pp. 1-7.

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Abstract

The catalytic stability of rice bran lipase has been determined in the presence of three denaturants viz, urea, GuHCI and GuHSCN. The enzyme is completely inactive above 7 M urea, 4 M GuHCI and 2 M GuHSCN concentration. The extent of denaturant interaction has been determined by the partial specific volume measurements of the enzyme. The preferential interaction parameter (~3) has values of 0.042, 0.064 and 0.075 g/g, and the denaturation volume changes are -180, -240 and -270 ml/mol in presence of 8 M urea, 6 M GuHCI and 3 M GuHSCN, respectively. The experimental values of number of denaturant molecules bound (A3) are 0.418, 0.566 and 0.320 g/g and the calculated values are 0.321, 0.511 and 0.632 g/g in presence of 8 M urea, 6 M GuHCI and 3 M GuHSCN, respectively. Fluorescence emission measurements indicated a decrease in the fluorescence emission intensity and a red shift in the emission maximum as the denaturant concentration is increased indicating the gradual exposure of aromatic chromophores. The instability of the enzyme in the presence of these denaturants has been indicated by a decreased value of apparent thermal denaturation temperature (Tm) of the enzyme from a control value of 67°C. The results obtained in the present study explain the extent of inactivation/stability of rice bran lipase in presence of these denaturants at different concentrations.

Item Type: Article
Uncontrolled Keywords: Rice bran lipase; Urea; GuHCI, Guanidine hydrochloride; GuHSCN, Guanidine thiocyanate; Preferential interaction; Thermal denaturation temperature
Subjects: 600 Technology > 08 Food technology > 21 Cereals > 01 Rice
500 Natural Sciences and Mathematics > 04 Chemistry and Allied Sciences > 29 Protein Chemistry
500 Natural Sciences and Mathematics > 04 Chemistry and Allied Sciences > 16 Enzyme Chemistry
Divisions: Protein Chemistry and Technology
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 28 Jun 2007 11:57
Last Modified: 18 Nov 2016 10:30
URI: http://ir.cftri.com/id/eprint/1276

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