Boonkaew B, Udompaisarn S, Arthan D, Somana J. Expression and characterization of a recombinant stevioside hydrolyzing β-glycosidase from Enterococcus casseliflavus.
Protein Expr Purif 2019;
163:105449. [PMID:
31295559 DOI:
10.1016/j.pep.2019.105449]
[Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 07/07/2019] [Accepted: 07/07/2019] [Indexed: 12/23/2022]
Abstract
The demand for steviol glycosides, non-caloric sweet components of Stevia rebaudiana Bertoni (stevia) leaves, has increased considerably as a benefit to enhance human health. However, the supply has remained challenging due to limited production, with the lack of a specific steviol glycoside hydrolyzing enzyme. In this study, a novel β-glucosidase (EcBgl) from Enterococcus casseliflavus was cloned and expressed in Escherichia coli. An EcBgl consists of 721 amino acids corresponding to a molecular mass of 79.37 kDa. The EcBgl was purified to homogeneity, followed by enzyme characterization. The enzyme showed optimum pH and temperature at 6.0 and 37 °C, and exhibited the kinetic constants kcat/Km for pNPG and kcat/Km for stevioside of 8583 mM-1s-1 and 95.41 mM-1s-1, respectively. When compared to the stevioside hydrolyzing β-glycosidases previously reported, EcBgl was found to be the most efficient enzyme. EcBgl also rendered hydrolysis of the stevioside to produce rubusoside, a rare steviol glycoside with a pharmaceutical solubilizing property, by cleaving at the glucose moiety. In addition, the enzyme demonstrated substantial resistance against amygdalin, so it served as a potential enzyme in agricultural and pharmaceutical applications.
Collapse