Abstract.
The activity of xanthine oxidoreductases (xanthine oxidase, XO, EC 1.2.3.2 and xanthine dehydrogenase, XDH, EC 1.1.1.204) in partially purified extracts of Gonyaulax polyedra was measured over 24 h both in a light:dark cycle and in constant light. This is the first demonstration of xanthine oxidoreductase in a unicellular alga. The activity of the O2-dependent form (XO) was found to be 15 times higher in light than in darkness. The same time-of-day specific differences persisted in constant light, demonstrating a control of XO by the circadian clock. In contrast, the activity of the NAD-dependent form (XDH) is not under circadian control. Because pharmacological inhibition of XO also blocks the effect of blue light on the Gonyaulax circadian clock, the possible relationship between XO and light reception in this unicellular alga will be discussed.
This is a preview of subscription content, log in via an institution to check access.
Author information
Authors and Affiliations
Additional information
Electronic Publication
Rights and permissions
About this article
Cite this article
Deng, TS., Roenneberg, T. The flavo-enzyme xanthine oxidase is under circadian control in the marine alga Gonyaulax. Naturwissenschaften 89, 171–175 (2002). https://doi.org/10.1007/s00114-002-0304-4
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/s00114-002-0304-4