Carbohydrate Self-Association Protein-like Oligomerization of Carbohydrates

Many proteins form noncovalent and thermodynamically reversible oligomers, and the state of self-association can dictate a proteins functionality. DNA-binding proteins are very often dimeric, while other proteins exist as trimers (e.g. chloramphenicol transacetylase), tetramers (e.g. hemoglobin), or higher-order reversible association products (tubulin, viral coat proteins, sickle cell hemoglobin), with clear functional roles that have never been observed for carbohydrates. Although weak self-association in a polysaccharide has been shown, Water-soluble aminocelluloses were prepared by the reaction of tosyl cellulose with an excess of di-or trifunctional amines, namely with tris(2-aminoethyl)amine yielding 6-deoxy-6-(2-(bis(2-aminoethyl)aminoethylamino) (BAEA) cellulose (1-3), as depicted in To ascertain whether the higher-order species are different oligomers, a simple logarithmic relationship between sedimentation coefficient s and molecular weight M can be utilized, namely s % M b or, equivalently, s i /s 1 % (M i /M 1 ) b , where 1 denotes the monomer, i denotes the i th species, and b is a power-law coefficient that depends on the conformation (ca. 0.2 for rods, 0.5 for coils, and 0.7 for spheres). [4] Taking the first observable species in each case as the monomer, all five of the 6-deoxy-6-aminocelluloses follow the power-law relation with b % 0.7, a value consistent wit