13319-32-9

Upstream product

• 13088-77-2 N,N',N'',N'''-tetraacetylchitotetraose 
• 53643-13-3 4-methylumbelliferyl β-D-N,N′,N′′-triacetylchitotrioside 
• 185628-87-9 2-methyl-4,5-dihydro-[4-O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-1,2-dideoxy-α-glucopyranoso][2,1-d]-1,3-oxazole 
• 81520-71-0 penta-N-acetylchitopentaose 
• 1398-61-4 chitin 

Downstream Products

• 13319-33-0 N,N',N'',N'',N'''',N'''''-hexaacetyl chitohexaose 
• 13088-77-2 N,N',N'',N'''-tetraacetylchitotetraose 
• 14200-67-0 N,N'-diacetylchitobiose 
• 7512-17-6 N-Acetyl-D-glucosamine 
• 81520-72-1 β-penta-N-acetylchitopentose 

Relevant academic research and scientific papers

Catalytic Depolymerization of Chitin with Retention of N-Acetyl Group

Chitin, a polymer of N-acetylglucosamine units with β-1,4-glycosidic linkages, is the most abundant marine biomass. Chitin monomers containing N-acetyl groups are useful precursors to various fine chemicals and medicines. However, the selective conversion of robust chitin to N-acetylated monomers currently requires a large excess of acid or a long reaction time, which limits its application. We demonstrate a fast catalytic transformation of chitin to monomers with retention of N-acetyl groups by combining mechanochemistry and homogeneous catalysis. Mechanical-force-assisted depolymerization of chitin with a catalytic amount of H2SO4 gave soluble short-chain oligomers. Subsequent hydrolysis of the ball-milled sample provided N-acetylglucosamine in 53 % yield, and methanolysis afforded 1-O-methyl-N-acetylglucosamine in yields of up to 70 %. Our process can greatly reduce the use of acid compared to the conventional process.

Introduction of a tryptophan side chain into subsite +1 enhances transglycosylation activity of a GH-18 chitinase from Arabidopsis thaliana, AtChiC

A tryptophan side chain was introduced into subsite +1 of family GH-18 (class V) chitinases from Nicotiana tabacum and Arabidopsis thaliana (NtChiV and AtChiC, respectively) by the mutation of a glycine residue to tryptophan (G74W-NtChiV and G75W-AtChiC). The specific activity toward glycol chitin of the two mutant enzymes was 70-71% of that of the wild type. Using chitin oligosaccharides, (GlcNAc)n (n = 4, 5 and 6), as the substrates, we found the transglycosylation reaction to be significantly enhanced in G74W-NtChiV and G75W-AtChiC when compared with the corresponding wild-type enzymes. The introduced tryptophan side chain might protect the oxazolinium ion intermediate from attack by a nucleophilic water molecule. The enhancement of transglycosylation activity was much more distinct in G75W-AtChiC than in G74W-NtChiV. Nuclear magnetic resonance titration experiments using the inactive double mutants, E115Q/G74W-NtChiV and E116Q/G75W-AtChiC revealed that the association constant of (GlcNAc)5 was considerably larger for the latter. Amino acid substitutions at the acceptor binding site might have resulted in the larger association constant for G75W-AtChiC, giving rise to the higher transglycosylation activity of G75W-AtChiC. The Author 2012. Published by Oxford University Press. All rights reserved.

Kinetics of hydrolysis of chitin/chitosan oligomers in concentrated hydrochloric acid

The kinetics of hydrolysis in concentrated hydrochloric acid (12.07 M) of the fully N-acetylated chitin tetramer (GlcNAc4) and the fully N-deacetylated chitosan tetramer (GlcN4) were followed by determining the amounts of the lower DP oligomers as a function of time. A theoretical model was developed to simulate the kinetics of hydrolysis of the three different glycosidic linkages in the tetramers. The model uses two different rate constants for the hydrolysis of the glycosidic bonds in the oligomers, assuming that the glycosidic bond next to one of the end residues are hydrolysed faster than the two other glycosidic linkages. The two rate constants were estimated by fitting model data to experimental results. The results show that the hydrolysis of the tetramers is a nonrandom process as the glycosidic bonds next to one of the end residues are hydrolysed 2.5 and 2.0 times faster as compared to the other glycosidic linkages in the fully N-acetylated and fully N-deacetylated tetramer, respectively. From previous results on other oligomers and the reaction mechanism, it is likely that the glycosidic bond that is hydrolysed fastest is the one next to the nonreducing end. The absolute values for the rate constants for the hydrolysis of the glycosidic linkages in GlcNAc4 were found to be 50 times higher as compared to the glycosidic linkages in GlcN4, due to the catalytic role of the N-acetyl group and the presence of the positively charged amino-group on the N-deacetylated sugar residue.

The amino acid sequence of satyr tragopan lysozyme and its activity

The amino acid sequence of satyr tragopan lysozyme and its activity was analyzed. Carboxymethylated lysozyme was digested with trypsin and the resulting peptides were sequenced. The established amino acid sequence had three amino acid substitutions at positions 103 (Asn to Ser), 106 (Ser to Asn), and 121 (His to Gln) comparing with Temminck's tragopan lysozyme and five amino acid substitutions at positions 3 (Phe to Tyr), 15 (His to Leu), 41 (Gln to His), 101 (Asp to Gly) and 103 (Asn to Ser) with chicken lysozyme. The time course analysis using N-acetylglucosamine pentamer as a substrate showed a decrease of binding free energy change, 1.1 kcal/mol at subsite A and 0.2 kcal/mol at subsite B, between satyr tragopan and chicken lysozymes. This was assumed to be responsible for the amino acid substitutions at subsite A-B at position 101 (Asp to Gly), however another substitution at position 103 (Asn to Ser) considered not to affect the change of the substrate binding affinity by the observation of identical time course of satyr tragopan lysozyme with turkey and Temminck's tragopan lysozymes that carried the identical amino acids with chicken lysozyme at this position. These results indicate that the observed decrease of binding free energy change at subsites A-B of satyr tragopan lysozyme was responsible for the amino acid substitution at position 101 (Asp to Gly).

Ring-opening glycosylation of a chitobiose oxazoline catalyzed by a non-chitinolytic mutant of chitinase

Ring-opening glycosylation of a chitobiose oxazoline was exclusively achieved by catalysis of a mutated chitinase that is only active for the glycosylation and not for chitinolysis.

Characterization and inhibitor studies of chitinases from a parasitic blowfly (Lucilia cuprina), a tick (Boophilus microplus), an intestinal nematode (Haemonchus contortus) and a bean (Phaseolus vulgaris)

The molecular weight pattern and the stage-specific activities of chitinases from the blowfly Lucilia cuprina, the tick Boophilus microplus and the intestinal nematode Haemonchus contortus were examined. Chitinolytic enzymes could be detected in all parasite species tested, but the activity was different between the stages. Highest chitinolytic titers were found in blowfly pupae (83 kDa, 118 kDa), hatching larvae of ticks (58 kDa, 94 kDa) and nematode eggs (43 kDa). Leaves from ethylene-treated bean plants Phaseolus vulgaris expressed two basic Class I chitinases (Ia, Ib) of 34 kDa, differing in their amino acid sequences at residue 33 and 34 (Ia: glycine, proline; Ib: lysine, aspartic acid). Inhibitor studies with blowfly pupae revealed that allosamidin (IC50 = 0.32 (±0.02) μM) was by far the best inhibitor when compared with various amino sugar derivatives. This compound also inhibited chitinases from tick larvae (IC50 = 0.69(±0.10) μM) and nematode eggs (IC50 = 0.048(±0.0045) μM) specifically. Whereas Class Ia chitinase from bean leaves was inhibited only up to 18% by 10 μM allosamidin, it had an IC50 of 1(±0.14) μM for the Ib type, which is the first plant chitinase described to be highly sensitive to allosamidin.

Glycosidase-catalysed Oligosaccharide Synthesis: Preparation of the N-Acetylchitooligosaccharides Penta-N-acetylchitopentaose and Hexa-N-acetylchitohexaose using the β-N-Acetylhexosaminidase of Aspergillus oryzae.

Using a crude β-N-acetylhexosaminidase from Aspergillus oryzae both tri-N-acetylchitotriose (GlcNAc)3 (1,n=1) and tetra-N-acetylchitotetraose (GlcNAc4) (1,n=2) act respectively as both glycosyl donor and glycosyl acceptor to give product mixtures containing significant quantities of the corresponding penta- and hexasaccharides which are readily isolated and purified by charcoal-Celite chromatography.