Effect of manganese extraction on oxygen generation and EPR signal II in spinach chloroplasts

✍ Scribed by Kuang-Yu Chen; Jui H. Wang

• Book ID: 104106081
• Publisher: Elsevier Science
• Year: 1974
• Weight: 780 KB
• Volume: 3
• Category: Article
• ISSN: 0006-3061
• DOI: 10.1016/s0006-3061(00)82012-8

✦ Synopsis

Removal of endogenous manganese from fresh ehlomplasts by incubation with solutions of magnesium ion was found to decrease-the efficiency of oxygen generation in the Hill reaction and increase the steady-state amplitude of Signal II. The efficiency of oxygen generation in the Hi reaction wss found t.o be directly proportional to the manganese content of the extra&xi sample, up to ahout 67yo extraction of the endogenous mangauge, where= the steady-state amplitude of Signal II wss found to be inversely proportional to the manganese eontent of the extracted ehloroplast sample. These observations suggest that in freshly prepared chloroplasts all lamellae-bound manganese atoms are equally active in catalyzing oxygen generation, and that Signal II may be due to a radical intermediate generated by the photo-oxidation of an electron carrier between the manganese complex and the chlorophyll molecules of PS II.