The Conformational Behaviour of Non-Hydrolizable Lactose Analogues: The Thioglycoside, Carbaglycoside, and Carba-Iminoglycoside Cases

Abstract

The conformational behaviours of several nonhydrolizable lactose analogues, namely methyl α-thiolactoside (1), methyl β-carbalactoside (2) and methyl β-carbaiminolactoside (3) have been studied using a combination of NMR spectroscopy [a]

Structural Analysis of Lac Repressor Bound to Allosteric Effectors

“…NMR studies have shown that replacement of an oxygen glycosidic bond with a thio glycosidic bond in lactose analogues increases the flexibility of the molecule. 22 The increased flexibility allows these molecules to adopt conformations that increase their binding affinity without jeopardizing the geometry of the galactoside required for stabilizing the induced conformation. Flexibility can also be achieved by the addition of a methylene group between the galactose ring and the C1 substituent group.…”

Structural Studies Using Unnatural Oligosaccharides: Toward Sugar Foldamers

“…To date, the attention has been directed mainly on the bioactivity of such compounds, neglecting the effect of the linkage modification on the overall oligosaccharide conformation. Little effort has been devoted to the structural features of these analogues. ,, Increased flexibility was observed for simple S- linked dimers (Figure ). Molecular mechanics calculations showed that the “standard” exo–syn (Φ) conformation of α-S- glycosides is significantly less rigid than the corresponding O- linked analogue .…”

Non-conventional Glycosidic Linkages: Syntheses and Structures of Thiooligosaccharides and Carbohydrates with Three-bond Glycosidic Connections

“…Another example is provided by the β-linked lactose derivatives 204 and 205 (Scheme 53). A similar analysis has shown [103] that both compounds adopt exo-anomeric conformations (syn-Φ) at the global minima on the Φ/Ψ-map. The orientations about the Ψ angle are, however, different: while the major conformer for O-glycosides is always centered at the syn-Ψ region, the anti-Φ conformer was found to be predominant for the S-lactose 204.…”