POLYNOIDIN: A MEMBRANE PHOTOPROTEIN ISOLATED FROM THE BIOLUMINESCENT SYSTEM OF SCALE‐WORMS

Abstract

Abstract— In order to isolate and purify the luminescence system of scale‐worms, the scales were homogenized and extracted in the presence of Triton X‐100. After chromatography on Bio‐Gel A‐5m, Sephadex G‐75 and DEAE‐cellulose, a single peak in luminescence activity was obtained. It showed properties of a membrane protein having a high mol. wt (about 500000) with characteristics of a photoprotein. The photoprotein, for which we suggest the name polynoidin , emits light in response to several reagents that can produce superoxide or hydroxyl radicals, such as H 2 O 2 plus Fe 2+ , but the luminescence is not triggered by Ca 2 + . Oxygen is an absolute requirement for the luminescent reaction. The luminescence has a maximum at 510 nm. The photoprotein is not fluorescent when excited at 350 nm either before or after the luminescent reaction, thus differing distinctly from the green‐fluorescent riboflavin in photosomes which is easily separated at the first step of the purification. We suggest a mechanism of the in vivo luminescence of scale worms in which the production of superoxide or hydroxyl radicals by the oxidation of reduced riboflavin could be regulated by Ca 2+ .