Chitin from crab shells

FideliTaq PCR Master Mix (USB, USA) was used for DNA amplification. T4 DNA ligase, T4
DNA polymerase, Klenow fragment, T4 polynucleotide kinase, shrimp alkaline
phosphatase (SAP), restriction enzymes and the protein molecular mass marker were
purchased from Fermentas (USA). The HiTrap Chelating HP column was purchased from GE
Healthcare (Uppsala, Sweden). Chitin from crab shells and Fluorimetric Chitinase
Assay Kit were purchased from Sigma-Aldrich (USA). Polyglucosamine (DA 0%) used for
the preparation of partially acetylated chitosans as well as α- and β-chitin were
kindly provided by Mahtani Chitosan (India). All other chemicals used for chitinase
analysis were of analytical grade.

NovaMatrix/FMC Biopolymer (Sandvika, Norway) kindly provided the high molecular weight chitosan (HMWc) with an acetylated unit content, FA, of 0.14 in the base form (GlcNH₂). The intrinsic viscosity, [η], was determined to be 988 mL/g and the viscosity average molecular weight determined to be 320,000 by capillary viscometry. Chitin from crab shells, phosphate buffered saline (PBS), deuterium oxide (D₂O), deuterium chloride (DCl), sodium deuterium oxide (NaOD), sodium nitrite (NaNO₂) and sodium hydroxide (NaOH) were all purchased from Sigma-Aldrich (St. Louis, MO, USA) The composition of PBS was 137 mM NaCl, 2.7 mM KCl and 10 mM phosphate buffer, with an ionic strength (I) of ~168 mM and pH of 7.4. Genipin was purchased from Challenge Bioproducts Co., Ltd. (Taiwan). All reagents and chemicals were of high purity. Deionized water was used for all preparations. Methodologies used are similar to those in [22 (link)].