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The most characteristic feature is the
α
-1,6-lingake, which gives the molecule
considerable conformational flexibility because of essentially free rotation
around 3 single bonds:
As a consequence, dextrans are not very expanded compared to 1,3 or 1,4
linked polysaccharides, but behave as random coils with low characteristic
ratios (C
∞
, typically 1.8) or persistence lengths (q).
In consequence of the large flexibility
α
-1,6 glucans have low intrinsic
viscosities and R
G
values, even at very high molecular weights. Example:
22
22 Reproduced from: E. Nordmeier (1993) J. Phys. Chem. 97, 5770-5785
O
CH
2
OH
HO
HO
O
O
O
CH
2
OH
HO
HO
O