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µÚһƪ£º 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 µÚ¶þƪ£ºGrasdalen H, Larsen B and Smidsrød O, A NMR study of the composition and sequence of uronate residue µÚÈýƪ£º Grasdalen H,Larsen B,Smidsrod O. A.P.M.R.study of the composition and sequence of uronate residues in alginates. Carbohydrate Research . 1979 ÆäËûµÄ¹úÍâµÄ¹ØÓÚ¸Ã×÷ÕߵĻòÕ߸÷½·¨µÄÎÄÕ¾ù»¶Ó¡£Ð»Ð»ÁË£¡Òò±È½Ï¾ÃÔ¶£¬Ò»Ö±Çó¶øÎ´µÃ£¡Çë¸÷λ´óÅ£ÏײßÏ×Á¦ ![]() |
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lemonbb8121
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2Â¥2013-01-12 08:08:23
lemonbb8121
ľ³æ (ÕýʽдÊÖ)
- Ó¦Öú: 13 (СѧÉú)
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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). |
3Â¥2013-01-12 08:11:17
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4Â¥2013-01-12 16:39:49














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