%0 Journal Article %1 VARUM1994 %A VARUM, K. M. %A OTTOY, M. H. %A SMIDSROD, O. %C THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, OXON, ENGLAND OX5 1GB %D 1994 %I ELSEVIER SCI LTD %J Carbohydr. Polym. %K ;; [ISI:] chitins chitosans; deacetylated field nmr-spectroscopy %N 2 %P 65 -- 70 %T WATER-SOLUBILITY OF PARTIALLY N-ACETYLATED CHITOSANS AS A FUNCTION OF PH - EFFECT OF CHEMICAL-COMPOSITION AND DEPOLYMERIZATION %V 25 %X The solubility of four partially N-acetylated chitosans with fraction of acetylated units (F-A) of 0.01, 0.17, 0.37 and 0.60 as a function of pH was investigated. The chitosan with F-A = 0.60 was soluble at all pH-values between 4 and 9. The solubility versus pH curve of the other chitosans, showed that all chitosans precipitated between pH 6 and 7.5, but with increasing solubility at higher pH-values with increasing F-A. Such solubility differences may have profound effects on enzyme accessability and biological effects of chitosans. The three chitosans with the lowest F-A values were depolymerised by treatment with nitrous acid, and the fraction of water-soluble material at pH 7.5 was determined. The almost fully deacetylated chitosan was completely insoluble at pH 7.5 in the depolymerisation range investigated, while the most acetylated chitosan (F-A = 0.60) was fully soluble at all pH-values. However, the two chitosans with F-A = 0.17 and 0.37 could be fractionated into a neutral-soluble and a neutral-insoluble fraction. The amount of neutral-soluble material increased with decreasing depolymerisation. The neutral-soluble and the neutral-insoluble fraction differed in both chemical composition and degree of polymerisation. Generally, the neutral-soluble fraction had a higher fraction of acetylated units and a lower degree of depolymerisation than the neutral-insoluble fraction. This compositional heterogeneity of the degraded chitosans was shown to be consistent with what is expected from the theoretical random degradation of chitosans with a Bernoullian (random) distribution of acetylated and deacetylated units.

@article{VARUM1994, __markedentry = {[phpts:6]}, abstract = {The solubility of four partially N-acetylated chitosans with fraction of acetylated units (F-A) of 0.01, 0.17, 0.37 and 0.60 as a function of pH was investigated. The chitosan with F-A = 0.60 was soluble at all pH-values between 4 and 9. The solubility versus pH curve of the other chitosans, showed that all chitosans precipitated between pH 6 and 7.5, but with increasing solubility at higher pH-values with increasing F-A. Such solubility differences may have profound effects on enzyme accessability and biological effects of chitosans. The three chitosans with the lowest F-A values were depolymerised by treatment with nitrous acid, and the fraction of water-soluble material at pH 7.5 was determined. The almost fully deacetylated chitosan was completely insoluble at pH 7.5 in the depolymerisation range investigated, while the most acetylated chitosan (F-A = 0.60) was fully soluble at all pH-values. However, the two chitosans with F-A = 0.17 and 0.37 could be fractionated into a neutral-soluble and a neutral-insoluble fraction. The amount of neutral-soluble material increased with decreasing depolymerisation. The neutral-soluble and the neutral-insoluble fraction differed in both chemical composition and degree of polymerisation. Generally, the neutral-soluble fraction had a higher fraction of acetylated units and a lower degree of depolymerisation than the neutral-insoluble fraction. This compositional heterogeneity of the degraded chitosans was shown to be consistent with what is expected from the theoretical random degradation of chitosans with a Bernoullian (random) distribution of acetylated and deacetylated units.}, added-at = {2011-11-04T13:47:04.000+0100}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, OXON, ENGLAND OX5 1GB}, author = {VARUM, K. M. and OTTOY, M. H. and SMIDSROD, O.}, biburl = {https://www.bibsonomy.org/bibtex/284c23dab9c4c37dca4a977422b136971/pawelsikorski}, citedref = {AMBRECHT W, 1919, BIOCHEM Z, V95, P108 ; ANTHONSEN MW, 1993, CARBOHYD POLYM, V22, P193 ; ANTHONSEN MW, 1994, IN PRESS CARBOHYDR P ; DOMARD A, 1987, INT J BIOL MACROMOL, V9, P98 ; DOMARD A, 1991, INT J BIOL MACROMOL, V13, P105 ; DRAGET KI, 1992, BIOMATERIALS, V13, P635 ; FRENSDORFF HK, 1963, J CHEM PHYS, V39, P2303 ; HAUG A, 1963, ACTA CHEM SCAND, V17, P1653 ; OTERLEI M, 1994, VACCINE, V12, P825 ; PAINTER TJ, 1968, ACTA CHEM SCAND, V22, P1637 ; ROBERTS GA, 1992, CHITIN CHEM, P116 ; SANNAN T, 1976, MAKROMOL CHEM, V177, P3589 ; VARUM KM, 1991, CARBOHYD RES, V211, P17 ; VARUM KM, 1991, CARBOHYD RES, V217, P19 ; VARUM KM, 1992, ADV CHITIN CHITOSAN, P127}, interhash = {90cebf6851b97d99c3578195fa97456a}, intrahash = {84c23dab9c4c37dca4a977422b136971}, isifile-dt = {Article}, isifile-ga = {PZ417}, isifile-j9 = {CARBOHYD POLYM}, isifile-nr = {15}, isifile-pi = {OXFORD}, isifile-rp = {VARUM, KM, UNIV TRONDHEIM,NORWEGIAN INST TECHNOL,DIV ; BIOTECHNOL,NOBIPOL,NORWEGIAN BIOPOLMER LAB,N-7034 TRONDHEIM,NORWAY.}, isifile-sc = {Chemistry, Applied; Chemistry, Organic; Polymer Science}, isifile-tc = {63}, issn = {0144-8617}, journal = {Carbohydr. Polym.}, keywords = {;; [ISI:] chitins chitosans; deacetylated field nmr-spectroscopy}, language = {English}, number = 2, owner = {phpts}, pages = {65 -- 70}, publisher = {ELSEVIER SCI LTD}, size = {6 p.}, sourceid = {ISI:A1994PZ41700001}, timestamp = {2011-11-04T13:47:27.000+0100}, title = {WATER-SOLUBILITY OF PARTIALLY N-ACETYLATED CHITOSANS AS A FUNCTION OF PH - EFFECT OF CHEMICAL-COMPOSITION AND DEPOLYMERIZATION}, volume = 25, year = 1994 }