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205205205

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[求助] 悬赏 carbohydrate research 的三篇文章,关于褐藻胶的核磁方法的

第一篇:

13C-n.m.r. studies of monomeric composition and sequence in alginate

Hans Grasdalen, Bjorn Larsen, Olav Smisrod Institute of Marine Biochemistry, N-7034 Trondheim-NTH NorwayReceived 14 April 1980

Accepted 2 June 1980

Available online 7 March 2001

http://dx.doi.org/10.1016/S0008-6215(00)85243-X, How to Cite or Link Using DOI



第二篇:Grasdalen H, Larsen B and Smidsrød O, A NMR study of the composition and sequence of uronate residue



第三篇:

Grasdalen H,Larsen B,Smidsrod O. A.P.M.R.study of the composition and sequence of uronate residues in alginates. Carbohydrate Research . 1979



其他的国外的关于该作者的或者该方法的文章均欢迎。谢谢了!因比较久远,一直求而未得!请各位大牛献策献力
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lemonbb8121

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Structure characterization of alginate and conformational behaviors of various alkali-metal alginates in solution
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lemonbb8121

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Structure characterization
of alginate and conformational behaviors
of various alkali-metal alginates in solution
Hiroyuki Kawarada 1, Asako Hirai 2, Hisashi Odani 2, Takeo lida 1, and Akio Nakajima t'*
1Department of Applied Chemistry, Osaka Institute of Technology, Asahi-ku, Osaka 535, Japan
2Institute for Chemical  Research, Kyoto University, Uji, Kyoto 611, Japan
Summary
The M/G ratio,  i.  e.,  number-ratio  of D-mannuronate  (M)  to L-gluronate
(G),  and diad  (MM, GG,  MG,  etc.)  and triad  (MMM,  MMG,  MGM,  etc.)  frequenci-
es were  determined with  i00 MHz  13C-NMR spectra  for two alginate  samples,
M-rich and G-rich samples.  The M/G ratios  obtained were  in accord with
those determined  from chemical  analysis  on hydrolyzedproducts  fairly well.
Molecular  chain dimensions  in solution were  investigated by viscosity
method  for five  alkali-metal  alginates  carrying  Li,  Na,  K,  Rb and Cs,  and
the results were discussed based on ion radius  and eleetronegativity  of
alkali-metals.  Finally,  ion-exchange  characteristics  of these alginates  by
Ca ++ ion were  interpreted with M/G ratio  and electronegativity.
Introduction
Alginic  acid is known  (1-3)  as a linear polysaccharide  of  (l-~)linked
~-L-guluronic  acid  (G)  and ~-D-mannuronic  acid  (M)  residues  arranged  in a
non-regular,  blockwise  fashion  along the  chain.  That is,  a chain is  compo-
sed  (i)  of M-block  including only M  residues,  G-block  including only G
residues,  and MG-heteroblock  including G  and M  residues.  The  chain conform-
ations  of M-block  and G-block were  suggested  (4,5)  to be  "flat-ribbon"  and
"buckled-ribbon"  forms,  respectively.  Both conformations  are drastically
different  each other,  hence,  the M/G ratio,  indicating  the number-ratio  of
M-residues  to G-residues  in the  chain,  is  an important measure  to discuss
the reactivity of the chain  such as the reaction  toward Ca ++ ion.  Gelation
of alginate  is responsible  to  "egg-box"  formation between  G-blocks  via Ca
ion  (6-8),  and solubility  of alginic acid  in acid is controlled by the MG-
heteroblocks  (9).
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