Evidence against Bicarbonate Bound in the O2-Evolving Complex of Photosystem II
Citations Over TimeTop 10% of 2008 papers
Abstract
The oxidation of water to molecular oxygen by photosystem II (PSII) is inhibited in bicarbonate-depleted media. One contribution to the inhibition is the binding of bicarbonate to the non-heme iron, which is required for efficient electron transfer on the electron-acceptor side of PSII. There are also proposals that bicarbonate is required for formation of O 2 by the manganese-containing O 2-evolving complex (OEC). Previous work indicates that a bicarbonate ion does not bind reversibly close to the OEC, but it remains possible that bicarbonate is bound sufficiently tightly to the OEC that it cannot readily exchange with bicarbonate in solution. In this study, we have used NH 2OH to destroy the OEC, which would release any tightly bound bicarbonate ions from the active site, and mass spectrometry to detect any released bicarbonate as CO 2. The amount of CO 2 per PSII released by the NH 2OH treatment is observed to be comparable to the background level, although N 2O, a product of the reaction of NH 2OH with the OEC, is detected in good yield. These results strongly argue against tightly bound bicarbonate ions in the OEC.
Related Papers
- → Evidence against Bicarbonate Bound in the O2-Evolving Complex of Photosystem II(2008)45 cited
- → Redox Tuning in Photosystem II(2016)13 cited
- → Elucidation of a multiple S3 intermediates model for water oxidation in the oxygen evolving complex of photosystem II. Calcium-assisted concerted O O bond formation(2022)10 cited
- → Reactivation of oxygen evolution of NaCl-washed Photosystem-II particles by Ca2+ and/or the 24 kDa protein(1985)64 cited
- → Effect of bicarbonate on the S2 multiline EPR signal of the oxygen‐evolving complex in photosystem II membrane fragments(1998)20 cited