Mouse Acidic Chitinase Effectively Degrades Random-Type Chitosan to Chitooligosaccharides of Variable Lengths under Stomach and Lung Tissue pH Conditions

Abstract

Chitooligosaccharides exhibit several biomedical activities, such as inflammation and tumorigenesis reduction in mammals. The mechanism of the chitooligosaccharides’ formation in vivo has been, however, poorly understood. Here we report that mouse acidic chitinase (Chia), which is widely expressed in mouse tissues, can produce chitooligosaccharides from deacetylated chitin (chitosan) at pH levels corresponding to stomach and lung tissues. Chia degraded chitin to produce N-acetyl-d-glucosamine (GlcNAc) dimers. The block-type chitosan (heterogenous deacetylation) is soluble at pH 2.0 (optimal condition for mouse Chia) and was degraded into chitooligosaccharides with various sizes ranging from di- to nonamers. The random-type chitosan (homogenous deacetylation) is soluble in water that enables us to examine its degradation at pH 2.0, 5.0, and 7.0. Incubation of these substrates with Chia resulted in the more efficient production of chitooligosaccharides with more variable sizes was from random-type chitosan than from the block-type form of the molecule. The data presented here indicate that Chia digests chitosan acquired by homogenous deacetylation of chitin in vitro and in vivo. The degradation products may then influence different physiological or pathological processes. Our results also suggest that bioactive chitooligosaccharides can be obtained conveniently using homogenously deacetylated chitosan and Chia for various biomedical applications.

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

“…We previously reported that the degradation products from β-chitin with higher D.D. were more abundant in comparison with αchitin [37,38]. In addition, the degradation products differ significantly between blockand random-type chitosan due to the substrate specificity of mouse Chia [38].…”

“…were more abundant in comparison with αchitin [37,38]. In addition, the degradation products differ significantly between blockand random-type chitosan due to the substrate specificity of mouse Chia [38]. The blocktype chitosan has amorphous regions with highly deacetylated areas (GlcN-rich), while in the random-type chitosan, the GlcNAc and GlcN residues are interspersed.…”

“…Chitooligosaccharides with a degree of polymerization of less than 10 are typically water-soluble, and it makes them an extremely valuable product in a wide range of industries. Porcine and mouse Chia recognize GlcNAc residues of chitosan and produce hetero-chitooligosaccharides [37,38].…”

“…Previously, we showed the pattern of chitooligosaccharide production from mealworm larvae and fly wings under chicken, pig, and marmoset gastrointestinal-like conditions [41]. Recently, we reported that mouse Chia effectively degrades random-type chitosan oligomers of variable lengths under pH conditions mimicking stomach and lung tissues [38]. Published data suggest that chitosan substrates could be good sources for chitooligosaccharide production by monkey CHIA.…”

“…Enzymatic methods using mammalian sources can reduce the cost while increasing the quality of production due to their safety and the simplicity of the process control [36]. 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].…”