alpha-Amylase (EC 22.214.171.124; alpha-D-1,4,glucan glucanohydrolase) catalyzes the hydrolysis of alpha-D-(1,4)-glucosidic linkages in starch, glycogen, and various malto-oligosaccharides, by releasing alpha-anomeric products. In this study, a novel method has been developed to prepare nanoprotein particles that carry alpha-amylase as a monomer by using a photosensitive microemulsion polymerization process. The nanostructured alpha-amylase with photosensitive features have been characterized by fluorescence spectroscopy, transmission electron microscopy (TEM) and Zeta Sizer. The fluorescence intensity of amylase nanoparticles was determined to be 658 a.u. at 610 nm and the average particle size of nanoamylase was found to be about 71.8 nm. Both free alpha-amylase and nanoparticles were used in the hydrolysis of starch under varying reaction conditions such as pH and temperature that affect enzyme activity and the results were compared to each other. Km values were 026 and 0.87 mM and V-max values were 0.36 IU mg(-1) and 22.32 IU mg(-1) for nanoenzyme and free enzyme, respectively. Then, thermal stability, storage stability and reusability were investigated and according to the results, activity was preserved 60% at 60 degrees C; 20% at 70-80 degrees C temperature values and 80% after 105 days storage. Finally after 10 cycles, the activity was preserved 90% and this novel enzymatic polymeric amylase nanoparticle has showed considerable potential as reusable catalyst. (C) 2012 Elsevier B.V. All rights reserved.