Crab-Eating Monkey Acidic Chitinase (CHIA) Efficiently Degrades Chitin and Chitosan under Acidic and High-Temperature Conditions.

Maiko Uehara,Fumitaka Oyama,Peter O Bauer,Yasusato Sugahara,Vaclav Matoska,Chinatsu Takasaki,Satoshi Wakita,Eri Tabata

doi:10.3390/molecules27020409

Abstract

Chitooligosaccharides, the degradation products of chitin and chitosan, possess anti-bacterial, anti-tumor, and anti-inflammatory activities. The enzymatic production of chitooligosaccharides may increase the interest in their potential biomedical or agricultural usability in terms of the safety and simplicity of the manufacturing process. Crab-eating monkey acidic chitinase (CHIA) is an enzyme with robust activity in various environments. Here, we report the efficient degradation of chitin and chitosan by monkey CHIA under acidic and high-temperature conditions. Monkey CHIA hydrolyzed α-chitin at 50 °C, producing N-acetyl-d-glucosamine (GlcNAc) dimers more efficiently than at 37 °C. Moreover, the degradation rate increased with a longer incubation time (up to 72 h) without the inactivation of the enzyme. Five substrates (α-chitin, colloidal chitin, P-chitin, block-type, and random-type chitosan substrates) were exposed to monkey CHIS at pH 2.0 or pH 5.0 at 50 °C. P-chitin and random-type chitosan appeared to be the best sources of GlcNAc dimers and broad-scale chitooligosaccharides, respectively. In addition, the pattern of the products from the block-type chitosan was different between pH conditions (pH 2.0 and pH 5.0). Thus, monkey CHIA can degrade chitin and chitosan efficiently without inactivation under high-temperature or low pH conditions. Our results show that certain chitooligosaccharides are enriched by using different substrates under different conditions. Therefore, the reaction conditions can be adjusted to obtain desired oligomers. Crab-eating monkey CHIA can potentially become an efficient tool in producing chitooligosaccharide sets for agricultural and biomedical purposes.

Highlights

Chitin is a β-1,4-linked polymer of the N-acetyl-D-glucosamine (GlcNAc) units [1,2].It is an integral component of the exoskeletons of crustaceans and insects, the microfilarial sheaths of parasitic nematodes and fungal cell walls [1,2,3]
We have reported that Chia residues in porcine pepsin preparations exhibit chitinolytic activity and degrade chitosan under stomach conditions [37], and that mouse Chia effectively produces variable length chitooligosaccharides from random-type chitosan [38]
We show that crab-eating monkey CHIA efficiently degrades the substrates while providing different sets of chitooligosaccharides under acidic and high-temperature conditions, and that the pattern and amount of such products can be regulated to achieve the enrichment of certain oligomers

Summary

Introduction

Chitin is a β-1,4-linked polymer of the N-acetyl-D-glucosamine (GlcNAc) units [1,2] It is an integral component of the exoskeletons of crustaceans and insects, the microfilarial sheaths of parasitic nematodes and fungal cell walls [1,2,3]. The conserved sequence in GH18 involved in catalysis is DXXDXDXE, where E is assumed to be the catalytic residue [11]. Both CHIT1 and CHIA digest natural chitin and chitosan, possibly through endo-chitinase activity [7,8,14]

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