Enzymatic depolymerization of lamellar single crystals of nigeran

Lamellar single crystals of the α-glucan: nigeran have been subjected to controlled enzymic degradation as an approach to understanding polysaccharide organization in these crystals. Analysis of both reactant and products by various methods argues that a situation exists where the crystals are inaccessible at 20°C but become increasingly accessible as the temperature approaches that of solution for the crystals in water. One has to conclude that chain folds are inaccessible to enzymes at 20°C and become increasingly accessible as one approaches the “melting temperature.” This could be due to increased mobility of the surface chains as temperature is raised, which produces large dynamic loops and makes enzyme degradation possible. The general conclusion is that nigeran single-crystal surfaces are disordered and increasingly mobile close to their dissolution temperature in water.