Photo control of enzyme activity of alpha-amylase.

Photo control of enzyme activity was performed by attaching a photochromic spiropyran compound to α-amylase. Modified α-amylase exhibited reverse photochromism in water: a colored form in the dark and a colorless form under light irradiation, which indicated that bound spiropyran possessed a hydrophilic structure (an open-ring form) in the dark and a hydrophobic structure (a closed-ring form) under light irradiation. The activity of modified α-amylase under light irradiation was extremely retarded as compared with that determined in the dark. The photo-induced change of the activity reversibly occurred in accordance with the photochromism of bound spiropyran. The mechanism of the photo control is discussed.