# Exo- and Endo-1,5-α-L-Arabinanases and Prebiotic Arabino-Oligosaccharides Production

## TL;DR

This paper reviews enzymes that produce prebiotic arabino-oligosaccharides, which can benefit gut health and have potential in food and pharmaceutical industries.

## Contribution

The first comprehensive analysis of exo- and endo-1,5-α-L-arabinanases for their role in producing arabino-oligosaccharides.

## Key findings

- Exo- and endo-ABNs from GH43 and GH93 families differ in structure and catalytic action.
- Exo-ABNs from GH93 exclusively release arabinobiose, while others produce varied AOS.
- AOS can stimulate beneficial gut bacteria and offer health benefits like blood sugar control.

## Abstract

There is growing interest in pentose-based prebiotic oligosaccharides as alternatives to traditional hexose-based prebiotics. Among these, arabino-oligosaccharides (AOS), derived from the enzymatic hydrolysis of arabinan polymers, have gained significant attention. AOS can selectively stimulate the growth of beneficial gut bacteria, including Bifidobacterium and Bacteroides species, and contribute to health-benefit functions such as blood sugar control, positioning AOS as a promising synbiotic candidate. For the industrial production of AOS, the development of efficient enzymatic processes is essential, with exo- and endo-1,5-α-L-arabinanases (exo- and endo-ABNs) playing a crucial catalytic role. Most ABNs belong to the glycoside hydrolase (GH) family 43, characterized by a five-bladed β-propeller fold structure. These enzymes hydrolyze internal α-1,5-L-arabinofuranosidic linkages, producing AOS with varying degrees of polymerization. Some ABNs GH43 were known to exhibit exo-type hydrolytic modes of action, producing specific AOS products such as arabinotriose. Additionally, exo-ABNs from GH93, which feature a six-bladed β-propeller fold, exclusively release arabinobiose through their exo-type catalytic mechanism. This review represents the first comprehensive analysis of exo- and endo-ABNs, offering scientific insights into their biotechnological potential for AOS production. It systematically compares enzyme classification, structural differences, catalytic mechanisms, paving the way for innovative applications in health, food, and pharmaceutical industries.