One-Pot Encapsulation of a Robust α-L-Rhamnosidase Mutant in Cu-MOF: A Recyclable Designed Biocatalyst for High-Yield Conversion of Icariin to Icariside I

Abstract

Icariside I is a pharmacologically important prenylated flavonoid glycoside, yet its efficient biocatalytic production from icariin is hindered by the limited stability and recyclability of the enzymes involved. In this study, an α-L-rhamnosidase mutant R783A (Rha R783A) was heterologously expressed, purified, and immobilized within a Cu-based metal–organic framework (MOF) via a one-pot co-precipitation strategy. The resulting Rha R783A@MOF biocomposite exhibited enhanced stability compared to the free enzyme, retaining >90% residual activity after incubation at 60 °C for 2 h and 86.4% after 30 days of storage. It also demonstrated broad pH adaptability. In the biotransformation of icariin, Rha R783A@MOF achieved a 99.8% conversion rate and a 97.8% yield of icariside I. Furthermore, the biocomposite maintained an 88.9% yield after eight consecutive reuse cycles under high-temperature conditions (60 °C), demonstrating excellent operational stability. This work presents a robust and sustainable strategy for icariside I production, highlighting the potential of MOF microparticles as an effective platform for the biocatalytic synthesis of high-value flavonoid compounds.