Photooxidation of Soybean Apoleghemoglobin with Protoporphyrin IX, Heme and Dye

Abstract

Soybean apoleghemoglobin a was irradiated with visible light in the presence of different sensitizers to probe the heme environment of the protein. With protoporphyrin IX as sensitizer, specific photooxidation of histidine‐92 and histidine‐61 occurred. Irradiation of oxyleghemolglobin and cyanleghemoglobin resulted in photooxidation of histidine‐92, while addition of methylene blue caused both histidine‐92 and histidine‐61 to be oxidized. Apoleghemoglobin, irradiated in the presence of rose bengal or methylene blue, lost tryptophan‐128 in addition to the two histidines. Copyright © 1978, Wiley Blackwell. All rights reserved