Taxonomic group: bacteria / Proteobacteria (Phylum: Proteobacteria)
 
NCBI PubMed ID: 16310757
Publication DOI: 10.1016/j.carres.2005.11.003
Journal NLM ID: 0043535
Publisher: Elsevier
Correspondence: Hongbin Zhang <hbzhangsjtu.edu.cn>
Institutions: School of Chemistry and Chemical Technology, Shanghai Jiao Tong University, Shanghai 200240, China, Department of Food & Nutrition, Faculty of Human Life Science, Osaka City University, Sumiyoshi, Osaka 558-5858, Japan

Curdlan was carboxymethylated in an aqueous alkaline medium using monochloroacetic acid as the etherifying agent. The structure of carboxymethylated curdlan (CMc) was analyzed by FT-IR and NMR spectroscopy, which revealed that the carboxymethyl group was introduced mainly at the C-6 position as well as at the C-2 and C-4 positions. Furthermore, CMc was compared with the native curdlan by using rheology and DSC methods. It was found that in water, both polysaccharides behaved as pseudoplastic fluids and fit the power law and Herschel-Bulkley rheological models well. Both the storage shear modulus G' and the loss shear modulus G'' of CMc aqueous solutions decreased and became more frequency dependent with decreasing concentration in comparison with the curdlan aqueous suspensions. The modulus-temperature curve also suggested that the gel characteristic of curdlan has been lost after chemical modification, which is consistent with the DSC results. AFM images revealed differences in the conformation of native and carboxymethylated curdlan, which changed from the aggregation of macromolecules to triple helices. All the experimental results suggest that the hydrogen bonds that bind curdlan with interstitial water to form the micelles have been destroyed completely and that the hydrophobic interactions related to the methylene groups at C-6 formed above 55 degrees C disappeared due to the introduction of the hydrophilic carboxymethyl group.

hydrogen bond, Rheology, Curdlan, carboxymethylation, physico-chemical property, gelation, hydrophobicity

Structure type: homopolymer
Location inside paper: p.90
Trivial name: glucan, β-1,3-glucan, curdlan, curdlan-type polysaccharide 13140, paramylon, curdlan, laminarin, β-glucan, curdlan, β-(1,3)-glucan, β-(1,3)-glucan, curdlan, curdlan, β-1,3-glucan, paramylon, reserve polysaccharide, b-glucan, β-1,3-D-glucan, laminaran, botryosphaeran, laminaran type β-D-glucan, latiglucan I, pachymaran, Curdlan, zymosan A, β-glucan, curdlan, laminarin, zymosan, zymosan, glucan particles, zymosan, β-(1-3)-glucan, β-(1,3)-glucan, β-(1,3)glucan, pachymaran, D-glucan (DPn)540, pachyman, laminaran, curdlan, zymosan, zymosan, β-(1,3)-glucan, zymosan A, zymosan, β-1,3-glucan, curdlan, β-1,3-glucan, curdlan, β-1,3-glucan, curdlan, pachyman, β-(1,3)-glucan, curdlan, callose, a water-insoluble β-(1→3)-glucan, fermentum β-polysaccharide, water-insoluble glucan, callose, laminarin, alkali-soluble β-glucan (PeA3), alkali-soluble polysaccharide (PCAP)
Compound class: EPS, O-polysaccharide, cell wall polysaccharide, lipophosphoglycan, glycoprotein, LPG, glucan, cell wall glucan, polysaccharide, glycoside, β-glucan, β-1, 3-glucan
Contained glycoepitopes: IEDB_1397514,IEDB_142488,IEDB_146664,IEDB_153543,IEDB_158555,IEDB_161166,IEDB_558869,IEDB_857743,IEDB_983931,SB_192
 
Methods: NMR, FTIR
Biosynthesis and genetic data: 0.19 and 0.24 M
 
Related record ID(s): 112990, 118123, 125281, 126051, 149482
NCBI Taxonomy refs (TaxIDs): 511
Reference(s) to other database(s): GTC:G51056AN, GlycomeDB:157, CCSD:50049, CBank-STR:4225, CA-RN: 51052-65-4, GenDB:FJ3380871.1
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NMR conditions: in D2O / 0.4M NaOD at 300(C) K       [as TSV]

13C NMR data: Linkage Residue C1 C2 C3 C4 C5 C6   bDGlcp 103.7 73.2 86.7 68.6 76.6 61.3

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