tailieunhanh - Báo cáo khoa học: Occurrence of glucosylsucrose [a-D-glucopyranosyl-(1fi2)-a-D-glucopyranosyl-(1fi2)-b-D-fructofuranoside] and glucosylated homologues in cyanobacteria Structural properties, cellular contents and possible function as thermoprotectants

Little is known about the structure and function of oligosaccharides in cyanobacteria. In this study, a new class of saccharides from Nostocwas identified by MS and NMR techniques, consisting of a-d-glucopyranosyl-(1fi2)-[a-d-glucopyranosyl-(1fi2)]n -b-d-fructofuranosides ranging from the trisaccharide (n¼1) to decasaccharide (n¼8). InNostoc ellipsosporumthe cell content of saccharides increased 10–20-fold after heat stress (1 day, 40 C) or during prolonged cultivation. | ềFEBS Journal Occurrence of glucosylsucrose a-D-glucopyranosyl- 1 fi2 -a-D-glucopyranosyl- 1 fi2 -p-D-fructofuranoside and glucosylated homologues in cyanobacteria Structural properties cellular contents and possible function as thermoprotectants Daniela Fischer1 Armin Geyer2 and Eckhard Loos3 1 Institut fur Organische Chemie Universitat Regensburg Germany 2 Fachbereich Chemie Philipps-Universitat Marburg Germany 3 Lehrstuhl fur Zellbiologie und Pflanzenphysiologie Universitat Regensburg Germany Keywords amylase cyanobacteria homologous series oligosaccharides thermoprotection Correspondence E. Loos Lehrstuhl fur Zellbiologie und Pflanzenphysiologie Universitat Regensburg UniversitatsstraBe 31 93053 Regensburg Germany Fax 49 941 943 3352 Tel 49 941 943 3042 E-mail . Present address MPI fur Biophysikalische Chemie Am Fassberg 11 37077 Gottingen Germany Received 24 August 2005 revised 31 October 2005 accepted 4 November 2005 doi Little is known about the structure and function of oligosaccharides in cyanobacteria. In this study a new class of saccharides from Nostoc was identified by MS and NMR techniques consisting of a-D-glucopyranosyl- 1fi2 - a-D-glucopyranosyl- 1fi2 n-b-D-fructofuranosides ranging from the trisaccharide n 1 to decasaccharide n 8 . In Nostoc ellipsosporum the cell content of saccharides increased 10-20-fold after heat stress 1 day 40 C or during prolonged cultivation. Under these conditions the abundance of homologues of higher molecular mass pentasaccharide increased and finally exceeded that of homologues of lower molecular mass including sucrose. Total intracellular content of the saccharides after heat stress was 5-10 mg- g dry weight -1 corresponding to intracellular concentrations of w v . A possible role of the oligosaccharides identified is in the protection of enzymes against heat inactivation. Whereas amylase from Nostoc was only weakly protected by the .