Effect of illumination with the visible polarized and nonpolarized light on alpha-amylolysis of starches of different botanical origin.

The alpha-amylolysis of potato, corn, waxy corn, and amaranthus starches with porcine pancreatic alpha-amylase upon illumination with visible polarized and nonpolarized light was studied. Samples were illuminated for 1 h either directly after blending the enzyme with starch or the enzyme solutions were illuminated for 1 h prior to the admixture of starch. Independently of the mode of illumination, no significant change in the hydrolysis kinetics was noted for corn, waxy corn, and amaranthus starches. The illumination of potato starch in the presence of alpha-amylase with polarized and nonpolarized light significantly accelerated the hydrolysis. In the first 5-h step the hydrolysis rate increased from 12.0 to 60.0 g x kg(-)(1) h(-)(1). Preillumination of enzyme in solution resulted in an increase in the rate of hydrolysis to 151.6 and 131.4 g x kg(-)(1) h(-)(1) after illumination with polarized and nonpolarized light, respectively. Circular dichroism spectra of alpha-amylase solutions stored in the dark and illuminated with visible polarized and nonpolarized light provided evaluation of the protein conformation, whereas exposure of enzyme solutions to the nonpolarized did not change the secondary structure of the protein. The illumination of the alpha-amylase solutions with polarized light significantly changed the amounts of alpha-helix and beta-form vs unilluminated samples: 42.3% and 25.5% vs 36.6% and 30.2%, respectively.