Determination of the degree of N-acetylation and the distribution of N-acetyl groups in partially N-deacetylated chitins (chitosans) by high-field n.m.r. spectroscopy

Vårum, Kjell M.; Anthonsen, Marit W.; Grasdalen, Hans; Smidsrød, Olav

doi:10.1016/0008-6215(91)84142-2

Cited by 408 publications

(210 citation statements)

References 11 publications

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“…The 1 H-175 NMR spectra were obtained at 85 ºC at 300 MHz (Oxford NMR 300 , Varian) (41,42). The 176 deuterium resonance was used as a field-frequency lock, and the chemical shifts were 177 referenced to internal sodium 3-(trimethylsilyl)propionate-d4 (0.00 p.p.m.).…”

Section: Experimental Procedures 125 126mentioning

confidence: 99%

Human Chitotriosidase-Catalyzed Hydrolysis of Chitosan

et al. 2011

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 3 ABSTRACT: Chitotriosidase (HCHT) is one of two family 18 chitinases produced by 45 humans, the other being acidic mammalian chitinase (AMCase). The enzyme is thought to be 46 part of the human defense mechanism against fungal parasites, but its precise role and the 47 details of its enzymatic properties have not yet been fully unraveled. We have studied 48properties of HCHT by analyzing how the enzyme acts on high molecular-weight chitosans, 49 soluble co-polymers of β-1,4-linked N-acetylglucosamine (GlcNAc, A) and glucosamine 50 (GlcN, D). Using methods for in-depth studies of the chitinolytic machinery of bacterial 51 family 18 enzymes, we show that HCHT degrades chitosan primarily via an endo-processive 52 mechanism, as would be expected on the structural features of its substrate-binding cleft. The 53 preferences of HCHT subsites for acetylated versus non-acetylated sugars were assessed by 54 sequence analysis of obtained oligomeric products showing a very strong, absolute, and a 55 relative weak preference for an acetylated unit in the -2, -1, +1 subsite, respectively. The 56 latter information is important for the design of inhibitors that are specific for the human 57 chitinases and also provide insight into what kind of products may be formed in vivo upon 58 administration of chitosan-containing medicines or food products. 59 KEYWORDS: Human chitinase; chitosan; chitin; processivity; chitotriosidase. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 4 Chitin, an insoluble linear polysaccharide consisting of repeated units of β-1,4-N-66 linked acetylglucosamine [(GlcNAc) n ], is common as a structural polymer in crustaceans, 67 arthropods, fungi, and parasitic nematodes. The metabolism of chitin in nature is controlled 68 by enzymatic systems that produce and break down chitin, primarily chitin synthases and 69 chitinases, respectively. Chitinases are thought to play important roles in anti-parasite 70 responses in several life forms, including humans (1-4). Even though chitin and chitin 71 synthases have not been found in humans, we produce two active chitinases that are 72 categorized as family 18 chitinases based on sequence-based classification of glycoside 73 hydrolases (5). These two enzymes are called acidic mammalian chitinase (AMCase) (6) and 74 human chitotriosidase (HCHT) (7) and both are believed to play roles in anti-parasite 75 responses (8, 9). While AMCase is found in the stomach (6), in tears (10), sinus mucosa (11), 76 and lungs (12), HCHT is primarily expressed in activated human macrophages (13). 77HCHT is up-regulated in a series of diseases and medical conditions such as 78Ga...

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Section: Experimental Procedures 125 126mentioning

confidence: 99%

Human Chitotriosidase-Catalyzed Hydrolysis of Chitosan

et al. 2011

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“…• Elemental analysis (Davies & Hayes, 1988;dos Santos et al, 2009); • Titration (Arcidiacono & Kaplan, 1992;Balázs & Sipos, 2007;de Alvarenga et al, 2010;Hattori et al, 1999;Park et al, 1983;Raymond et al, 1993;Tôei & Kohara, 1976;Zhanga et al, 2011); • Hydrolytic methods (Davies & Hayes, 1988;Nanjo et al, 1991;Niola et al, 1993;Sato et al, 1998;Zamani et al, 2008); • HPLC -Ultraviolet (Aiba, 1986;Muzzarelli & Rocchetti, 1985); • Infrared (Baxter et al, 1992;Duarte et al, 2002;Kasaai, 2008;Miya et al, 1980;Moore & Roberts, 1980;Sannan et al, 1978); • 1 H nuclear magnetic resonance (Brugnerotto et al, 2001;de Alvarenga et al, 2010;Fernandez-Megia et al, 2005;Lavertu et al, 2003;Varum et al, 1991); • CP-MAS 13 C NMR (Heux et al, 2000;Manni et al, 2010;Raymond et al, 1993); • CP-MAS 15 N NMR (Kasaai, 2009;Yu et al, 1999); • Many other methods are described in the literature but with a somewhat smaller appeal. Some of these methods are: steric exclusion chromatography (Brugnerotto et al, 2001), nitrous acid deamination (Sashiwa et al, 1991), thermal analysis (Garcia Alonso et al, 1983), gas chromatography with columns packed with chitin and chitosan (Muzzarelli et al, 1980),...…”

Section: Introductionmentioning

confidence: 99%

Characterization and Properties of Chitosan

Alvarenga¹

2011

Biotechnology of Biopolymers

123

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“…Furthermore, the resonance at around 4.6 ppm corresponded to the H-1 of the N-acetylglucosamine unit (GlcNAc). The resonance at around 2.0 ppm represents three protons in the acetyl group [12]. The resonances of H-3, 4, 5, and 6 appeared in the range of 3.5-4.0 ppm [12].…”

Section: Synthesis and Characterization Of Htccmentioning

confidence: 96%

Positively Charged Nanostructured Lipid Carriers and Their Effect on the Dissolution of Poorly Soluble Drugs

et al. 2016

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Abstract:The objective of this study is to develop suitable formulations to improve the dissolution rate of poorly water soluble drugs. We selected lipid-based formulation as a drug carrier and modified the surface using positively charged chitosan derivative (HTCC) to increase its water solubility and bioavailability. Chitosan and HTCC-coated lipid particles had higher zeta-potential values than uncoated one over the whole pH ranges and improved encapsulation efficiency. In vitro drug release showed that all NLC formulations showed higher in vitro release efficiency than drug particle at pH 7.4. Furthermore, NLC formulation prepared with chitosan or HTCC represented good sustained release property. The results indicate that chitosan and HTCC can be excellent formulating excipients of lipid-based delivery carrier for improving poorly water soluble drug delivery.

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Determination of the degree of N-acetylation and the distribution of N-acetyl groups in partially N-deacetylated chitins (chitosans) by high-field n.m.r. spectroscopy

Cited by 408 publications

References 11 publications

Human Chitotriosidase-Catalyzed Hydrolysis of Chitosan

Human Chitotriosidase-Catalyzed Hydrolysis of Chitosan

Characterization and Properties of Chitosan

Positively Charged Nanostructured Lipid Carriers and Their Effect on the Dissolution of Poorly Soluble Drugs

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