Iodine binding capacity and iodine binding energy of glycogen

The iodine binding capacity (IBC) of glycogen is around 0.30% (w/w) at 3°C. The amount of iodine complexed comprises about 12.5% of the mass of glycogen that takes part in the glycogen–iodine (GI) complex formation. This suggests involvement of four iodine atoms for every 25 anhydroglucose units (AGU, C₆H₁₀O₅). Since the chromophore is due to the I₄ unit within the helix of 11 AGUs, only 44% of the AGUs (11 out of 25) are involved in the complex formation. The heat of formation of the GI complex is around ?40 kJ/mol of I₂ bonded. These results suggest remarkable similarities with those of the amylopectin–iodine (API) complex. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1409–1412, 1997