Water in Crystalline Fibers of Dihydrate β-Chitin Results in Unexpected Absence of Intramolecular Hydrogen Bonding

Abstract

The complete crystal structure (including hydrogen) of dihydrate β-chitin, a homopolymer of N-acetylglucosamine hydrate, was determined using high-resolution X-ray and neutron fiber diffraction data collected from bathophilous tubeworm Lamellibrachia satsuma. Two water molecules per N-acetylglucosamine residue are clearly localized in the structure and these participate in most of the hydrogen bonds. The conformation of the labile acetamide groups and hydroxymethyl groups are similar to those found in anhydrous β-chitin, but more relaxed. Unexpectedly, the intrachain O3-H…O5 hydrogen bond typically observed for crystalline β,1–4 glycans is absent, providing important insights into its relative importance and its relationship to solvation.

Two-way traffic of glycoside hydrolase family 18 processive chitinases on crystalline chitin

“…However, we cannot simply compare the velocities of the chitinases and cellulase because the crystalline substrates are different. In particular, crystalline b-chitin used in this study contains water molecules in the crystal 7 , which may strongly influence the activities of glycan hydrolases. Assuming that each processive movement involves catalysis, the moving velocities suggest that a single catalytic process takes 0.014 and 0.021 s for ChiA and ChiB, respectively, whereas TrCel7A needs 0.14 s (ref.…”

“…The never-dried tubes kept in deionized water were cut into B3 cm lengths and were then deproteinized according to the method described previously 26 . After overnight immersion in 1 N NaOH solutions at room temperature, they were treated with 0.3% NaClO 2 solutions buffered at pH 4.9 in 0.1 M acetate buffer at 70°C for 3 h 7,26 . Recombinant chitinase A (ChiA) and chitinase B (ChiB) from the chitinolytic bacteria S. marcescens were heterologously expressed in Escherichia coli DH5a cells harbouring plasmids pNCA112 carrying the cloned chiA gene 27 and pMCB7 carrying the cloned chiB gene 28 for ChiA and ChiB, respectively.…”

“…Since the molecular chains of chitin are packed with parallel orientation in the crystal 7 , the processive movement of the enzyme molecules can be directly visualized using the procedure described in our previous reports on HS-AFM studies of processive cellulases from the cellulolytic ascomycete Trichoderma reesei [8][9][10] . There was an advantage of using chitinases rather than cellulases for the present work: the chitinolytic bacterium S. marcescens 11 produces only two extracellular processive chitinases, ChiA and ChiB, and these two enzymes comprise one of the best studied pairs of processive enzymes acting on cellulose/chitin 12 .…”

Effect of purification method of β-chitin from squid pen on the properties of β-chitin nanofibers

“…where I1-10 is the maximum intensity of the [1][2][3][4][5][6][7][8][9][10] mixed plane and Iam is the intensity of the amorphous diffraction at 16° [23]. d-Spacing was determined using Bragg's law, which states that…”

“…-Chitin has antiparallel molecular chains with hydrogen bonds between the chains. On the other hand, -chitin is purified from squid pens, tubeworm housing tubes, diatom spines, etc., and the lower natural abundance compared to -chitin [7]. The anhydrous -chitin has parallel molecular chains without significant hydrogen bonds between intermolecular sheets [8,9].…”