title: Acidic mammalian chitinase is a proteases-resistant glycosidase in mouse digestive system.
abstract: Chitinases are enzymes that hydrolyze chitin, a polymer of β-1, 4-linked N-acetyl-D-glucosamine (GlcNAc). Chitin has long been considered as a source of dietary fiber that is not digested in the mammalian digestive system. Here, we provide evidence that acidic mammalian chitinase (AMCase) can function as a major digestive enzyme that constitutively degrades chitin substrates and produces (GlcNAc)2fragments in the mouse gastrointestinal environment. AMCase was resistant to endogenous pepsin C digestion and remained active in the mouse stomach extract at pH 2.0. The AMCase mRNA levels were much higher than those of four major gastric proteins and two housekeeping genes and comparable to the level of pepsinogen C in the mouse stomach tissues. Furthermore, AMCase was expressed in the gastric pepsinogen-synthesizing chief cells. The enzyme was also stable and active in the presence of trypsin and chymotrypsin at pH 7.6, where pepsin C was completely degraded. Mouse AMCase degraded polymeric colloidal and crystalline chitin substrates in the gastrointestinal environments in presence of the proteolytic enzymes. Thus, AMCase can function as a protease-resistant major glycosidase under the conditions of stomach and intestine and degrade chitin substrates to produce (GlcNAc)2, a source of carbon, nitrogen and energy.
authors.affiliation: Department of Chemistry and Life Science, Kogakuin University, Hachioji, Tokyo 192-0015, Japan.
authors.forename: Misa
authors.initials: M
authors.lastname: Ohno
authors.affiliation: Department of Chemistry and Life Science, Kogakuin University, Hachioji, Tokyo 192-0015, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kimura
authors.affiliation: Laboratory for Structural Neuropathology, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan.|Department of Neuroscience for Neurodegenerative Disorders, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan.|Laboratory of Structural Neuropathology, Doshisha University Graduate School of Brain Science, Kyotanabe-shi, Kyoto 610-0394 Japan.
authors.forename: Haruko
authors.initials: H
authors.lastname: Miyazaki
authors.affiliation: Department of Chemistry and Life Science, Kogakuin University, Hachioji, Tokyo 192-0015, Japan.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Okawa
authors.affiliation: Department of Chemistry and Life Science, Kogakuin University, Hachioji, Tokyo 192-0015, Japan.
authors.forename: Riho
authors.initials: R
authors.lastname: Onuki
authors.affiliation: Department of Chemistry and Life Science, Kogakuin University, Hachioji, Tokyo 192-0015, Japan.
authors.forename: Chiyuki
authors.initials: C
authors.lastname: Nemoto
authors.affiliation: Department of Chemistry and Life Science, Kogakuin University, Hachioji, Tokyo 192-0015, Japan.
authors.forename: Eri
authors.initials: E
authors.lastname: Tabata
authors.affiliation: Department of Chemistry and Life Science, Kogakuin University, Hachioji, Tokyo 192-0015, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Wakita
authors.affiliation: Department of Chemistry and Life Science, Kogakuin University, Hachioji, Tokyo 192-0015, Japan.
authors.forename: Akinori
authors.initials: A
authors.lastname: Kashimura
authors.affiliation: Department of Chemistry and Life Science, Kogakuin University, Hachioji, Tokyo 192-0015, Japan.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Sakaguchi
authors.affiliation: Department of Chemistry and Life Science, Kogakuin University, Hachioji, Tokyo 192-0015, Japan.
authors.forename: Yasusato
authors.initials: Y
authors.lastname: Sugahara
authors.affiliation: Laboratory for Structural Neuropathology, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan.|Department of Neuroscience for Neurodegenerative Disorders, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan.|Laboratory of Structural Neuropathology, Doshisha University Graduate School of Brain Science, Kyotanabe-shi, Kyoto 610-0394 Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Nukina
authors.affiliation: Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA.
authors.forename: Peter O
authors.initials: PO
authors.lastname: Bauer
authors.affiliation: Department of Chemistry and Life Science, Kogakuin University, Hachioji, Tokyo 192-0015, Japan.
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Oyama
mesh_terms: D000117:Acetylglucosamine / Q000378:metabolism; D000818:Animals; D002686:Chitin / Q000378:metabolism; D002688:Chitinases / Q000378:metabolism*; D010450:Endopeptidases / Q000378:metabolism; D005753:Gastric Mucosa / Q000378:metabolism*; D005944:Glucosamine / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006868:Hydrolysis; D008322:Mammals / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D010434:Pepsin A / Q000378:metabolism; D010435:Pepsinogens / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D010435:Pepsinogens; D012333:RNA, Messenger; D002686:Chitin; D006026:Glycoside Hydrolases; C499255:AMCase, mouse; D002688:Chitinases; D010450:Endopeptidases; D010447:Peptide Hydrolases; D010434:Pepsin A; C020557:gastricsin; D005944:Glucosamine; D000117:Acetylglucosamine