ISSN:
0170-2041
Schlagwort(e):
Chemistry
;
Organic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Beschreibung / Inhaltsverzeichnis:
Conformational Analysis, XXV. - Conformations of Octasaccharide and Pentasaccharide Sequences in N-Glycoproteins of the Lactosamine TypeThe oligosaccharide sequences [β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man(1 → 3)]β-D-Gal-(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man(1 → 6)β-D-Man(1 → 4)-D-GlcNAc (2), β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man(1 → 6)β-D-Man(1 → 4)-D-GlcNAc (3), β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)-α-D-Man(1 → 3)β-D-Man(1 → 4)-D-GlcNAc (4), and β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man-OMe (5), found in N-glycoproteins, were investigated by means of HSEA calculations with the program GESA to reveal the preferred solution conformations of these compounds. Experimental evidence of the calculated conformations was given by 1H and 13C NMR studies like NOE experiments, spin-lattice relaxation-time measurements and observation of special deshielding effects. NMR spectra analysis required application of 2-D-NMR techniques. As a conclusion of experimental and theoretical results the common sequences in the saccharides 2, 3, 4, and 5 exhibit very similar conformations. The pentasaccharide 4 takes up a linear conformation whereas 5 shows a bent arrangement of the pyranose rings (‚gt conformation‘) which results in a relatively close contact between the α-D-Man unit and the reducing D-GlcNAc unit. Analogously, both conformations, the linear and the bent one, occur in the octasaccharide 2.
Notizen:
Die bevorzugten Konformationen der in N-Glycoproteinen vorkommenden Oligosaccharid-Sequenzen [β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man(1 → 3)] β-D-Gal(1 → 4)β-D-GlcNAc-(1 → 2)α-D-Man(1 → 6)β-D-Man(1 → 4)-D-GlcNAc (2), β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man(1 → 6)β-D-Man(1 → 4)-D-GlcNAc (3), β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man(1 → 3)-β-D-Man(1 → 4)-D-GlcNAc (4) und β-D-Gal(1 → 4)β-D-GlcNA(1 → 2)α-D-Man-OMe (5) wurden durch HSEA-Berechnungen mit dem Programm GESA bestimmt. Die Überprüfung der Rechnungen erfolgte durch 1H- und 13C-NMR-spektroskopische Experimente wie NOE-Untersuchungen, Spin-Gitter-Relaxationszeitmessungen und Beobachtung spezieller Abschirmungseffekte. Die Interpretation der NMR-Spektren erfolgte mit Hilfe von 2-D-NMR-Techniken. Die in 2, 3, 4, und 5 gemeinsam auftretenden Sequenzen haben alle sehr ähnliche bevorzugte Konformationen. Während 4 eine weitgehend gestreckte Konformation aufweist, zeigt 5 bevorzugt eine gebogene gt-Konformation, bei der die α-D-Man-Einheit der reduzierenden D-GlcNAc-Einheit nahe steht. Beide Formen kommen in 2 entsprechend vereint vor.
Zusätzliches Material:
10 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/jlac.198519850309
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