# Structural Analysis of Laminarin-Derived Oligosaccharides Produced by Transglycosylation of Exo-β-1,3-glucanase ScEXG1 from Saccharomyces cerevisiae

## TL;DR

This study shows how an enzyme from yeast can create prebiotic sugars from laminarin, revealing new possibilities for producing health-benefiting compounds.

## Contribution

The paper identifies new transglycosylation products and their structures using ScEXG1 under mild conditions.

## Key findings

- ScEXG1 produces a trisaccharide DP3 and two tetrasaccharides DP4–1 and DP4–2 from laminaribiose.
- Structural analysis reveals DP3 as β-Glc-(1→6)-β-Glc-(1→3)-Glc and DP4 variants.
- Transglycosylation occurs efficiently at low enzyme dosage and specific substrate concentrations.

## Abstract

Exo-β-1,3-glucanase
EXG1 (ScEXG1) from Saccharomyces
cerevisiae hydrolyzes β-1,3-glucans and exhibits
transglycosylation activity, enabling biocatalytic synthesis of prebiotic
oligosaccharides. In this study, recombinant ScEXG1–6 ×
His was tested with laminaribiose as both the donor and acceptor.
Under low-enzyme dosage, transglycosylation products were detected
across a range of substrate concentrations (4.38–32.85 mM),
with 21.9 mM laminaribiose producing 270.70 ± 10.32 nmol/mL of
the main trisaccharide product-DP3 (DP3) after 3 h. Structural elucidation
by HPLC-ESI-MS/MS identified DP3 as β-Glc-(1→6)-β-Glc-(1→3)-Glc
based on glycosidic and cross-ring fragmentation patterns. Two additional
tetrasaccharides were also characterized as β-Glc-(1→3)-β-Glc-(1→6)-β-Glc-(1→3)-Glc
(DP4–1) and β-Glc-(1→6)-β-Glc-(1→3)-β-Glc-(1→3)-Glc
(DP4–2). The findings highlight ScEXG1’s ability to
produce structurally diverse β-glucan oligosaccharides under
mild conditions, thereby expanding enzymatic strategies for prebiotic
oligosaccharide production.