Cmgc. Renard et Mc. Jarvis, Acetylation and methylation of homogalacturonans 1: optimisation of the reaction and characterisation of the products, CARBOHY POL, 39(3), 1999, pp. 201-207
Tetrabutylammonium (TBA) salts of homogalacturonans, obtained by acid hydro
lysis of demethylated citrus pectins, were acetylated and/or methylated. Me
thylation took place in DMSO, using CH3I as the reagent, and was stoichiome
tric up to a degree of methylation (DM) of >60. The best acetylation result
s, with acetic anhydride as reagent, were obtained using formamide as solve
nt and pyridine as catalyst, giving degrees of acetylation (DAc) of up to 1
50% in a single step. The reaction was fast but demanded large excess of ac
etic anhydride. Acetylation occurred on both the O-2 and the O-3 position,
with a slight preference for O-2, of galacturonic acid residues. The hydrod
ynamic volume of the molecules showed little change after derivatisation. A
cetylation inhibited hydrolysis of homogalacturonans by endopolygalacturona
se. (C) 1999 Elsevier Science Ltd. All rights reserved.