Immobilization of an Endo-β-N-acetylglucosaminidase for the Release of Bioactive N-glycans

Potential applications of recombinant bifidobacterial proteins in the food industry, biomedicine, process innovation and glycobiology

Bifidobacterial proteins have been widely studied to elucidate the metabolic mechanisms of diet adaptation and survival of Bifidobacteria, among others. The use of heterologous expression systems to obtain proteins in sufficient quantities to be characterized has been essential in these studies. L. lactis and the same Bifidobacterium as expression systems highlight ways to corroborate some of the functions attributed to these proteins. The most studied proteins are enzymes related to carbohydrate metabolism, particularly glycosidases, due to their potential application in the synthesis of neoglycoconjugates, prebiotic neooligosaccharides, and active metabolites as well as their high specificity and efficiency in processing glycoconjugates. In this review, we classified the recombinant bifidobacterial proteins reported to date whose characterization has demonstrated their usefulness or their ability to produce a product of commercial interest for the food industry, biomedicine, process innovation and glycobiology. Future directions for their study are also discussed.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-021-00957-1.

Effects of Industrial Thermal Treatments on the Release of Bovine Colostrum Glycoprotein N-Glycans by Endo-β-N-acetylglucosaminidase

N-Glycans are structurally similar to human milk oligosaccharides, the gold standard prebiotics for infants. Bovine milk N-glycans released by endo-β-N-acetylglucosaminidase (EndoBI-1) were shown to have similar prebiotic selectivity as human milk oligosaccharides, explaining the interest for N-glycan recovery for use as prebiotics. Industrial thermal treatments such as high-temperature short-time (HTST) and ultra-high-temperature (UHT) might favor the enzymatic deglycosylation of N-glycans through promoting protein denaturation. We investigated the effects of HTST (72 °C for 15 s) and UHT (135 °C for 3 s) on N-glycan release from bovine colostrum glycoproteins by nonimmobilized and amino-immobilized EndoBI-1. A total of 104 N-glycans including isomers/anomers were identified by high-resolution mass spectrometry. In both EndoBI-1 forms, HTST increased the release of N-glycans; however, the impact of UHT on releasing N-glycans was comparable to the nonthermal treatment. Although the amino-immobilized enzyme similarly released neutral N-glycans as the free form, it released fewer sialylated and fucosylated N-glycans.

Mass spectrometry-based qualitative and quantitative N-glycomics: An update of 2017-2018

N-glycosylation is one of the most frequently occurring protein post-translational modifications (PTMs) with broad cellular, physiological and pathological relevance. Mass spectrometry-based N-glycomics has become the state-of-the-art instrumental analytical pipeline for sensitive, high-throughput and comprehensive characterization of N-glycans and N-glycomes. Improvement and new development of methods in N-glycan release, enrichment, derivatization, isotopic labeling, separation, ionization, MS, tandem MS and informatics accompany side-by-side wider and deeper application. This review provides a comprehensive update of mass spectrometry-based qualitative and quantitative N-glycomics in the years of 2017-2018.

Co-Immobilization of Tri-Enzymes for the Conversion of Hydroxymethylfurfural to 2,5-Diformylfuran

Acting as a "green" manufacturing route, the enzyme toolbox made up of galactose oxidase, catalase, and horseradish peroxidase can achieve a satisfactory yield of 2,5-diformylfuran derived from 30 mM hydroxymethylfurfural. However, as the concentration of hydroxymethylfurfural increases, the substrate causes oxidative damage to the activity of the tri-enzyme system, and the accumulated hydrogen peroxide produced by galactose oxidase causes tri-enzyme inactivation. The cost of tri-enzymes is also very high. These problems prevent the utilization of this enzyme toolbox in practice. To address this, galactose oxidase, catalase, and horseradish peroxidase were co-immobilized into Cu3(PO4)2 nanoflowers in this study. The resulting co-immobilized tri-enzymes possessed better tolerance towards the oxidative damage caused by hydroxymethylfurfural at high concentrations, as compared to free tri-enzymes. Moreover, the 2,5-diformylfuran yield of co-immobilized tri-enzymes (95.7 ± 2.7%) was 1.06 times higher than that of separately immobilized enzymes (90.4 ± 1.9%). This result could be attributed to the boosted protective effect provided by catalase to the activity of galactose oxidase, owing to the physical proximity between them on the same support. After 30 recycles, co-immobilized tri-enzymes still achieves 86% of the initial yield. Moreover, co-immobilized tri-enzymes show enhanced thermal stability compared with free tri-enzymes. This work paves the way for the production of 2,5-diformylfuran from hydroxymethylfurfural via co-immobilized tri-enzymes.

Alkaline Modification of a Metal–Enzyme–Surfactant Nanocomposite to Enhance the Production of L-α-glycerylphosphorylcholine

Microenvironment modification within nanoconfinement can maximize the catalytic activity of enzymes. Phospholipase A1 (PLA1) has been used as the biocatalyst to produce high value L-α-glycerylphosphorylcholine (L-α-GPC) through hydrolysis of phosphatidylcholine (PC). We successfully developed a simple co-precipitation method to encapsulate PLA1 in a metal–surfactant nanocomposite (MSNC), then modified it using alkalescent 2-Methylimidazole (2-Melm) to promote catalytic efficiency in biphasic systems. The generated 2-Melm@PLA1/MSNC showed higher catalytic activity than PLA1/MSNC and free PLA1. Scanning electron microscopy and transmission electron microscopy showed a typical spherical structure of 2-Melm@PLA1/MSNC at about 50 nm, which was smaller than that of 2-Melm@MSNC. Energy disperse spectroscopy, N2 adsorption isotherms, Fourier transform infrared spectrum, and high-resolution X-ray photoelectron spectroscopy proved that 2-Melm successfully modified PLA1/MSNC. The generated 2-Melm@PLA1/MSNC showed a high catalytic rate per unit enzyme mass of 1.58 μmol mg-1 min-1 for the formation of L-α-GPC. The 2-Melm@PLA1/MSNC also showed high thermal stability, pH stability, and reusability in a water–hexane biphasic system. The integration of alkaline and amphiphilic properties of a nanocomposite encapsulating PLA1 resulted in highly efficient sequenced reactions of acyl migration and enzymatic hydrolysis at the interface of a biphasic system, which cannot be achieved by free enzyme.

Immobilized Biocatalysts

An application-related definition for immobilized enzymes was given by Chibata in 1978 […]