Scavenging of Superoxide Generated in Photosystem I by Plastoquinol and Other Prenyllipids in Thylakoid Membranes

• Published in: Biochemistry (Easton) Vol. 42; no. 28; pp. 8501 - 8505
• Main Authors: Kruk, Jerzy, Jemioła-Rzemińska, Małgorzata, Burda, Kvetoslava, Schmid, Georg H, Strzałka, Kazimierz
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 22-07-2003
• Subjects: Light; Lipid Metabolism; Models, Biological; Oxygen - metabolism; Photosynthetic Reaction Center Complex Proteins - metabolism; Photosynthetic Reaction Center Complex Proteins - radiation effects; Photosystem I Protein Complex; Plastoquinone - analogs & derivatives; Plastoquinone - metabolism; Protein Prenylation; Spinacia oleracea - metabolism; Superoxides - metabolism; Thylakoids - metabolism
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi034036q

We have examined scavenging of a superoxide by various prenyllipids occurring in thylakoid membranes, such as plastoquinone-9, α-tocopherolquinone, their reduced forms, and α-tocopherol, measuring oxygen uptake in hexane-extracted and untreated spinach thylakoids with a fast oxygen electrode under flash-light illumination. The obtained results demonstrated that all the investigated prenyllipids showed the superoxide scavenging properties, and plastoquinol-9 was the most active in this respect. Plastoquinol-9 formed in thylakoids as a result of enzymatic reduction of plastoquinone-9 by ferredoxin-plastoquinone reductase was even more active than the externally added plastoquinol-9 in the investigated reaction. Scavenging of superoxide by plastoquinol-9 and other prenyllipids could be important for protecting membrane components against the toxic action of superoxide. Moreover, our results indicate that vitamin K1 is probably the most active redox component of photosystem I in the generation of superoxide within thylakoid membranes.