Identification, purification and characterization of a novel glycosidase (BgLm1) from Leuconostoc mesenteroides
2020
Pino-García, Raquel del | Porrelli, Annalisa | Rus-Fernández, Patricia | Segura-Carretero, Antonio | Curiel, José Antonio
This study describes the identification and characterization of a novel recombinant Leuconostoc mesenteroides glycosidase (BgLm1). Since the protein encoded by LEUM_0847 gene was annotated as putative β-glucosidase, characterization procedures were done using p-nitrophenyl-β-d-glucopyranoside as substrate. A high yield of purified recombinant BgLm1 was obtained (12 mg/L). The enzyme showed an optimal activity at pH 6.0 and 40 °C and preserved 65% of residual activity after 48 h of incubation at 25 °C. Ca²⁺ and Mn²⁺ ions greatly increased the β-glucosidase activity. Moreover, BgLm1 demonstrated β-galactosidase and β-fucosidase activities. Kinetic parameters of BgLm1 revealed its low affinity to p-nitrophenyl-β-d-glucopyranoside (Kₘ of 9.93 mmol/L).Then, although LEUM_0847 gene was annotated as a β-glucosidase, our results suggest that BgLm1can be indeed considered as a β-galactosidase since high hydrolysis using skimmed milk (lactose) as natural substrate and high affinity (Kₘ of 0.56 mmol/L) and specific constant (2254 mmol/L⁻¹ s⁻¹) to p-nitrophenyl-β-d-galactopyranoside were observed. In conclusion, the enzymatic properties observed in this study, support the interest of BgLm1 for food industrial applications.
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