Photo-modulation of horseradish peroxidase activity via covalent attachment of carboxylated-spiropyran dyes

The photo-modulation of the enzyme horseradish peroxidase modified with pho tochromic spiropyran dyes is reported. The degree of photo-modulation, grea ter than 90% reduction in enzyme activity under visible compared to UV illu mination, matches the greatest degree of photo-modulation previously report ed in the literature. The observation that only a small fraction of the con jugated photochromic molecules are photo-switched suggests that the dyes in fluence the enzyme activity via local interaction with the enzyme active si te. (C) 1999 Elsevier Science B.V. All rights reserved.