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.
%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
}