Configurational and Conformational Aspects of Carbohydrate Biochemistry

Conformation, dynamics, solvation and relative stabilities of selected β-hexopyranoses in water: a molecular dynamics study with the gromos 45A4 force field

“…Enzyme-catalyzed epimerizations (through epimerases) almost exclusively involve phosphorylated sugars. 20,362 However, data exist for the enzymatic Glc!Man epimerization 363 (via fructose), with an estimated free-energy difference of 3.07 kJ mol À1 . Metal complexes can also catalyze epimerization at the C 2 carbon.…”

“…Ring conformation: Pyranose systems may present at least eight relevant conformers in solution 1,2,18,20,[41][42][43][44] (which are most easily distinguished geometrically by means of appropriate pseudorotation variables 20,[45][46][47][48][49][50][51][52][53], namely two chair forms (originally labelled C1 and 1C or, more recently, 4 C 1 and 1 C 4 ) and six boat forms (labelled 1,4 B, 2,5 B, 3,0 B, B 1,4 , B 2,5 and B 3,0 ). Skewboat forms may also be of relevance for some systems.…”

Etude structurale par diffraction des rayons X d'un dianhydride glycofurannique: bis(O-acétyl-3 désoxy-5α-D-xylofurannose) dianhydride-1,2':2,1'

“…Les cycles furanniques adoptent la conformation enveloppe 4E (Bentley, 1972). Les atomes C(4) ou C(4P), C(4S), C(4T) en position endo, s'~cartent en moyenne de 0,59 A des plans moyens d+finis par C(1), C(2), C(3), 0(4) ou atomes homologues.…”

Structure cristalline du mélézitose monohydraté

“…L'atome C'(4), en position endo c'est-5.-dire du m~me c6t6 que C'(6) par rapport 5. ce plan, s'en 6carte plus que C'(3) qui se trouve en position exo. La conformation adopt6e par le cycle furannique est donc 4T 3 (Bentley, 1972). Cette m~me conformation se retrouve dans le r6sidu fructofurannosyl du plant6ose, du raffinose et du sucrose (Tableau 7).…”