Open AccessCharacterization of lyso‐galactolipids, C‐2 and C‐3 O ‐acyl trigalactosylglycerol isomers, obtained from the lichenized fungus Dictyonema glabratum
Author(s) -
Sassaki Guilherme L,
Gorin Philip A.J,
Iacomini Marcello
Publication year - 2001
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2001.tb09461.x
Subject(s) - chemistry , glycerol , moiety , stereochemistry , galactolipid , galactolipids , residue (chemistry) , glycolipid , hydrolysis , degree of unsaturation , nuclear magnetic resonance spectroscopy , fatty acid , organic chemistry , phospholipid , biochemistry , chloroplast , membrane , gene
A mixture of two lyso isomers of a galactolipid was obtained from Dictyonema glabratum . Aqueous hydrolysis gave rise to galactose and glycerol in a 3:1 molar ratio. ESI–MS spectroscopy gave, in the positive‐ion mode, a pseudomolecular ion at m / z 839 and daughter ions with m / z 677, 600, 515 and 353, suggesting three galactosyl units linked to a glycerol moiety, substituted by one O ‐acyl group. 1D and 2D NMR experiments were used to characterize the glycolipid, and HMQC examination showed three anomeric signals, corresponding to two α‐Gal p and one β‐Gal p residue liked to glycerol. The glycolipid structure was shown to be O ‐α‐ D ‐Gal p ‐(1→6)‐ O ‐α‐ D ‐Gal p ‐(1→6)‐ O ‐β‐ D ‐Gal p ‐(1↔1)‐2‐ and ‐3‐monoacyl‐ D ‐glycerol, the latter structures not having been previously found in nature. The fatty acid composition was determined by GC–MS of derived methyl esters: that of palmitic acid C 16:0 was the most abundant, although the presence of C 12:0 , C 14:0 , C 16:1 and C 18:0 esters was observed.