Abstract
Transient ESR spectra of the membrane fragments of Heliobacterium modesticaldum are observed at X-band (9 GHz). In plant photosystem(PS)I,both P700+ and A1-radicals show symmetric broad ESR spectra with peak-to-peak linewidth of 8-10G statically. ESR spectra after flash excitation show the spin polarized pattern of A/E/A from low magnetic field (E:emission,A:absorption) that are attributed to the P700+A1-. ESR spectrum of P800+ in H.modesticaldum shows lineshape similar to that of P700+. However, the spin-polarized radical pair in H.modesticaldum shows the pattern of E/A/E and seems to be ascribable to the P800+Fx-. We will calculate ESR lineshape based on the model.
