Angles glycosidic

Figure 5. Intersaccharide hydrogen bonds (dotted lines) and the glycosidic angle 0 (05-01-04 -04 ) between site A and B. These hydrogen bonds and 0 (= -86 ) are similar to those found for cellulose.

Feasible models were required to have glycosidic angles between 1130 and 1220. 

Until now, the conformation of a complexed maltose seemed to be very close to that of free maltose in the crystalline state (Fig. 14.3) (Jeffrey and Sundaralingam 1981). The conformation of each cycle is The torsion angles are O-5 -C-l -O-l -C-4 = +116 and C-r-O-r-C-4-C-3 = +122 . The glycosidic angle C-l -O-l -C-4 is 120 . There is an intermolecular hydrogen bond 0-3—H—0-2. ... 

It is interesting to add that simple modifications of the glycosidic angle x. which fixes the base plane with respect to the phosphodiester backbone, are also a powerful way of provoking important conformational transitions. This was demonstrated in early modeling by Olson which lead to unusual ribbon-like structures of DNA. More recently, it has been shown that such deformations are related to certain protein induced DNA deformations, leading to the so-call TA-DNA conformation and to the conformations created by extreme stretching of the double helix (see Section 3.5 and Protein-Nucleic Acid Interactions). 

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