1.Solution Structure of Molecular Associations Investigated Using NMR for Polysaccharides: Xanthan/Galactomannan Mixtures.
Takemasa M1, Nishinari K2. J Phys Chem B. 2016 Mar 31;120(12):3027-37. doi: 10.1021/acs.jpcb.5b11665. Epub 2016 Mar 18.
Although the intermolecular nuclear Overhauser effect (NOE) signal was valuable to elucidate molecular association structure, it could not always be observed for associated molecules due to the short spin-spin relaxation time T2 in NMR measurements, especially for high molar mass systems. While almost no study has been reported for high molar mass polymers (>1 × 10(6)), especially for polysaccharide-polysaccharide interactions, NOE signals were observed for the first time between two different types of polysaccharides, xanthan and galactomannan (locust bean gum), forming a synergistic gel, as a direct evidence of intermolecular binding of polysaccharides. The NOE peak was found between pyruvic acid in xanthan and anomeric proton of mannose of galactomannan. This NOE signal was observed only when mixing time >0.5 s, indicating indirect NOEs caused by spin diffusion. Therefore, this NOE could not be used to construct the molecular models.
2.Effect of carboxymethylation on rheological and drug release characteristics of locust bean gum matrix tablets.
Chakravorty A1, Barman G2, Mukherjee S3, Sa B4. Carbohydr Polym. 2016 Jun 25;144:50-8. doi: 10.1016/j.carbpol.2016.02.010. Epub 2016 Feb 17.
This study was undertaken to investigate correlation between the carboxymethylation-induced rheological changes and drug release characteristics of locust bean gum (LBG) matrix tablets. LBG was derivatized to carboxymethyl LBG (CMLBG) and characterized by (13)C NMR, FTIR and elemental analyses. Rheological studies revealed that LBG, in contact with water, produced a strong elastic gel which swelled less due to lower penetration of water resulting in slower drug release. On the other hand, CMLBG formed a viscous polymer solution through which higher influx of water resulted in rapid swelling of the matrix and faster drug release. Although the release from a particular matrix was dependent on drugs' solubilities, CMLBG matrix tablet produced faster release of all the drugs than LBG matrix tablets. In conclusion, rheological study appeared to be an useful tool to predict release of drugs from polysaccharide matrix tablets.
3.Preparation and characterization of tragacanth-locust bean gum edible blend films.
Mostafavi FS1, Kadkhodaee R2, Emadzadeh B3, Koocheki A4. Carbohydr Polym. 2016 Mar 30;139:20-7. doi: 10.1016/j.carbpol.2015.11.069. Epub 2015 Nov 30.
The present work introduces the structure and physicomechanical properties of a novel blend film made from binary solutions of gum tragacanth (GT) and locust bean gum (LBG) at different mixing ratios. Apparent viscosities and surface tensions of individual and blend gum solutions were also investigated. The viscosity data indicated that there was a distinct synergism between the two gums at all mixing ratios. FTIR spectra showed the existence of noncovalent intermolecular interactions between gums. The surface tensions of binary solutions were significantly lower than those of individual gums which is advantageous for coating applications. All films had homogenous and smooth surface morphology and their transparency, water vapour barrier and mechanical properties were improved by incorporating LBG in blend. The results of this study suggest that GT-LBG blend film, owing to its desirable properties, has the potential to be used as a new degradable food packaging material.
4.An extremely alkaline mannanase from Streptomyces sp. CS428 hydrolyzes galactomannan producing series of mannooligosaccharides.
Pradeep G C1, Cho SS2, Choi YH1, Choi YS1, Jee JP1, Seong CN3, Yoo JC4. World J Microbiol Biotechnol. 2016 May;32(5):84. doi: 10.1007/s11274-016-2040-5. Epub 2016 Apr 2.
An alkaline-thermostable mannanase from Streptomyces sp. CS428 was produced, purified, and biochemically characterized. The extracellular mannanase (Mn428) was purified to homogeneity with 12.4 fold, specific activity of 2406.7 U/mg, and final recovery of 37.6 %. The purified β-mannanase was found to be a monomeric protein with a molecular mass of approximately 35 kDa as analyzed by SDS-PAGE and zymography. The first N-terminal amino acid sequences of mannanase enzyme were HIRNGNHQLPTG. The optimal temperature and pH for enzyme were 60 °C and 12.5, respectively. The mannanase activities were significantly affected by the presence of metal ions, modulators, and detergents. Km and Vmax values of Mn428 were 1.01 ± 3.4 mg/mL and 5029 ± 85 µmol/min mg, respectively when different concentrations (0.6-10 mg/mL) of locust bean gum galactomannan were used as substrate. The substrate specificity of enzyme showed its highest specificity towards galactomannan which was further hydrolyzed to produce mannose, mannobiose, mannotriose, and a series of mannooligosaccharides.