Glucopyranose rings

Fig. 1. Schematic diagram of two glucopyranose units of a cycloamylose molecule illustrating details of the o-(l,4) glycosidic linkage and the numbering system employed to describe the glucopyranose rings.

Cycloamyloses are cyclic oligosaccharides made up of D-glucopyranose rings in a a-1,4 linkage (Fig. 1), Cycloamyloses with six, seven, and eight glucose units have been extensively studied (for review, see 6, 18, 26, 27). 

Spherical polar coordinates are used for conformational representation of pyranose rings in the C-P system. Unlike the free pseudorotation of cyclopentane, the stable conformations of cyclohexane conformers are in deeper energy wells. Even simong the (less stable) equatorial (6 = 90 ) forms, pseudorotation is somewhat hindered. Substitutions of heteroatoms in the ring and additions of hydroxylic or other exocyclic substituents further stabilize or destabilize other conformers compared to cyclohexane. A conformational analysis of an iduronate ring has been reported based on variation of < ) and 0 (28), and a study of the glucopyranose ring... 

V. Spiwok, B. Kralova, and I. Tvaroska, Modelling of P-D-glucopyranose ring distortion in different force fields a metadynamics study, Carbohydr. Res., 345 (2010) 530-537. 

Lysozyme catalyzes the hydrolysis of the polysaccharide component of plant cell walls and synthetic polymers of j8(l — 4)-linked units of A-acetylglucosamine (NAG) (Chapter 1). It is expected from studies on nonenzymatic reactions that one of the intermediates in the hydrolytic reaction is a oxocarbenium ion in which the conformation of the glucopyranose ring changes from a full-chair to a sofa (half-chair) conformation (Chapter 1). The transition state analogue I, in which the lactone ring mimics the carbonium ion-like transition state n, binds tightly to lysozyme = 8.3 X 10 8M.10... 

The Angle Between Adjacent Hydroxyl Groups of the D-Glucopyranose Ring... 

Cellulose (1-11) and amylose starch do not contain carbon-carbon double bonds but they are also geometrical isomers. Both consist of 1,4-linked D-glucopyranose rings, and the difference between them is in configuration at carbon 1. As a result, cellulose is highly crystalline and is widely applied as a structural material while the more easily hydrolyzed starch is used primarily as food. 

Marszalek PE, Oberhauser AF, Pang YP and Fernandez JM (1998) Polysaccharide elasticity governed by chair-boat transitions of the glucopyranose ring. Nature, 396 661-4 Marx-Figini M (1969) On the biosynthesis of cellulose in higher and lower plants. In Marchessault RH (ed), Proceedings of 6th cellulose conference. WUey, New York Mason DC (ed) (1975) Sawmill Techniques for Southeast Asia. Miller Freeman, San Francisco... 

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