Rational design of L-arabinose isomerase from <i>Lactobacillus fermentum</i> and its application in D-tagatose production.

Juan LI; Jing WU; Sheng Chen; Wei Xia

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Rational design of L-arabinose isomerase from Lactobacillus fermentum and its application in D-tagatose production.

Author: Juan LI ¹ ; Jing WU ¹ ; Sheng CHEN ¹ ; Wei XIA ¹
Author Information

1. State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, Jiangsu, China.
Publication Type:Journal Article
Keywords: D-galactose; D-tagatose; L-arabinose isomerase; conversion rate; rational design
MeSH: Galactose/metabolism*; Limosilactobacillus fermentum/genetics*; Lactose; Hexoses/metabolism*; Aldose-Ketose Isomerases/genetics*; Hydrogen-Ion Concentration
From: Chinese Journal of Biotechnology 2023;39(3):1107-1118
CountryChina
Language:Chinese
Abstract: L-arabinose isomerase (L-AI) is the key enzyme that isomerizes D-galactose to D-tagatose. In this study, to improve the activity of L-arabinose isomerase on D-galactose and its conversion rate in biotransformation, an L-arabinose isomerase from Lactobacillus fermentum CGMCC2921 was recombinantly expressed and applied in biotransformation. Moreover, its substrate binding pocket was rationally designed to improve the affinity and catalytic activity on D-galactose. We show that the conversion of D-galactose by variant F279I was increased 1.4 times that of the wild-type enzyme. The K_m and k_cat values of the double mutant M185A/F279I obtained by superimposed mutation were 530.8 mmol/L and 19.9 s^-1, respectively, and the catalytic efficiency was increased 8.2 times that of the wild type. When 400 g/L lactose was used as the substrate, the conversion rate of M185A/F279I reached a high level of 22.8%, which shows great application potential for the enzymatic production of tagatose from lactose.