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Open and closed states of Candida antarctica lipase B: protonation and the mechanism of interfacial activation

DOI: 10.1194/jlr.M063388 DOI Help
PMID: 26447231 PMID Help

Authors: Benjamin Stauch (EMBL) , Stuart J. Fisher (Diamond Light Source) , Michele Cianci (EMBL)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Lipid Research , VOL 56 , PAGES 2348 - 2358

State: Published (Approved)
Published: December 2015

Open Access Open Access

Abstract: Lipases (EC are ubiquitous hydrolases for the carboxyl ester bond of water-insoluble substrates, such as triacylglycerols, phospholipids, and other insoluble substrates, acting in aqueous as well as in low-water media, thus being of considerable physiological significance with high interest also for their industrial applications. The hydrolysis reaction follows a two-step mechanism, or “interfacial activation,” with adsorption of the enzyme to a heterogeneous interface and subsequent enhancement of the lipolytic activity. Among lipases, Candida antarctica lipase B (CALB) has never shown any significant interfacial activation, and a closed conformation of CALB has never been reported, leading to the conclusion that its behavior was due to the absence of a lid regulating the access to the active site. The lid open and closed conformations and their protonation states are observed in the crystal structure of CALB at 0.91 Å resolution. Having the open and closed states at atomic resolution allows relating protonation to the conformation, indicating the role of Asp145 and Lys290 in the conformation alteration. The findings explain the lack of interfacial activation of CALB and offer new elements to elucidate this mechanism, with the consequent implications for the catalytic properties and classification of lipases.

Journal Keywords: Fatty Acid; Metabolism; Lipids; Chemistry; Enzymology; Enzyme Regulation; X-Ray Crystallography

Subject Areas: Biology and Bio-materials

Facility: DESY

Added On: 15/12/2015 15:52

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