Abstract
Photosystem 2 preparations with very high rates of oxygen evolution from the thermophilic cyanobacterium Phormidium laminosum have been studied by EPR spectrometry. In the presence of DCMU the g = 1.82 signal of the iron—quinone electron acceptor (Q) can be observed. It is proposed that DCMU is necessary to disrupt a magnetic interaction, between the semiquinone forms of Q and the secondary acceptor B, which otherwise prevents detection of the Q −Fe signal. A doublet EPR signal arising from magnetic interaction between Q −Fe and the reduced intermediary electron acceptor pheophytin (I −), and a spin-polarized triplet signal assumed to arise from the back reaction between I − and P680 + can also be seen. Preliminary redox titrations of Q reduction have been carried out, indicating E m ⋍ 0 mV.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
