Efficient biosynthesis of naringenin-ɑ-maltoside by amylosucrase obtained from Deinococcus planocerae

Abstract

Naringenin, a flavanone (flavonoid family) has bioactive effects, such as antioxidant, free radical scavenging, anti-inflammatory, carbohydrate metabolism, and immunoregulatory effects on the human body. However, its low water solubility and bioavailability limit its use in food, pharmaceutical, cosmetic, and drug industries. Amylosucrase (ASase, E. C. 2.4.1.4), uses sucrose as a substrate and is a glycosyltransferase that hydrolyzes glucose and fructose generating a glycosylated product. In this study, the putative ASase gene (accession number: WP_102128133.1) from Deinococcus planocerae KCTC 33809 (DplAS) was expressed in Escherichia coli. The optimum reaction temperature and pH for sucrose hydrolytic capacity of DplAS were determined to be 30 °C and 7.0, respectively. DplAS was determined to have a half-life of 256.7 and 42.8 min at 40 °C and 45 °C, respectively. Although it exhibited high similarity with DgAS (80%), DplAS displayed different acceptor specificities to that of DgAS. Uniquely, DplAS generated one major product (naringenin-maltoside) via transglycosylation using sucrose and naringenin as donor and acceptor molecules, respectively. Based on NMR, naringenin-maltoside was identified as naringenin-4′-O-α-D-maltopyranoside, and its conversion rate was optimized using the response surface method (RSM) with central composite design (CCD). This resulted in a donor to acceptor ratio of 25.9:1 at 27.64 °C, and a 55.69% conversion of sucrose.