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Cell Biochem Biophys (2015) 71:11991206
DOI 10.1007/s12013-014-0329-2
ORIGINAL PAPER
The Surfactant-Induced Conformational and Activity Alterations in Rhizopus niveus Lipase
Parvez Alam Gulam Rabbani Gamal Badr
Badr Mohamed Badr Rizwan Hasan Khan
Published online: 26 November 2014 Springer Science+Business Media New York 2014
Abstract In this study, we have reported the effect of nonionic, anionic, cationic, and zwitterionic detergents on the enzymatic activity and structural stability of Rhizopus niveus lipase. Secondary structural changes were monitored by Far-UV CD which shows that surfactant induces helicity in the Rhizopus niveus lipase protein which was maximum in case of CTAB followed by SDS, CHAPS, and Brij-35. Similarly, tertiary structural changes were monitored by tryptophan uorescence. We also carried out enzyme kinetics assays which showed that activity was enhanced by 1.5- and 1.1-fold in the presence of CHAPS and Brij-35, respectively. Furthermore, there was a decline in activity by 20 and 30 % in case of SDS and CTAB, respectively. These studies may be helpful in understanding detergentlipase interaction in greater detail as lipases are used in many industrial processes.
Keywords Rhizopus niveus lipase ANS Fluorescence
intensity Mean residual ellipticity
Introduction
Living organisms produce several classes of lipolytic enzymes which include lipase (EC 3.1.1.3) and nonlipolyticesterases (EC 3.1.1.1). Lipases are enzyme that catalyzes the hydrolysis of ester linkages in long-chain triacylglycerols with concomitant release of the constituent acid and alcohol moieties. Lipase catalyzes not only the hydrolysis of ester bond of triacylglycerol but also the synthesis of ester bonds and transesterication. Transesterication by lipases is particularly important in industry. They act at the interface between an insoluble substrate phase and an aqueous phase in which the enzyme is dissolved. Lipases are ubiquitously produced by plants, animals, and microorganisms [13]. Microbial lipases are the preferred potent sources due to several industrial potentials [4]. The world market for lipases has been estimated at approximately US$20 million of the industrial enzyme market [5]. Lipases have been intensively investigated for their multiplexity of catalysis with unique specicities [6] which have multifold applications in oleochemistry, organic synthesis, detergent formulations, and nutrition [7]. Also lipases display useful properties related to their stability as organic solvent-tolerant [5] and thermostable [8] enzymes.
In general, lipases are 2060 kD proteins with an active Ser residue of the active site...