Abstract
The heliobacteria are strictly anaerobic photosynthetic bacteria that belong to Gram-positive bacteria. RC of Heliobacteria contain Fe-S type RC. Fe-S type RCs are able to photoreduce NADP+ via ferredoxin (Fd), although it has not been proven yet in heliobacteria. We investigated electron transfer process from heliobactrial RC to Fd by NADP+ photoreduction and ESR spectroscopy. The absorption spectra of the purified Fd A, B and C from Heliophilum fasciatum and g values of cryogenic ESR spectra were typical of those of the 2[4Fe-4S] cluster type. Fd A decreased an absorbance of 385 nm under air condition, and their half life were 6 h respectively. The purified RC fraction was contained cytochromes. NADP+ photoreduction activity with spinach FNR were showed by Fd B and C. However, illuminated ESR spectroscopy in the presence of each Fds and purified RC from H. fasciatum were shown typical of reduced Fe-S cluster.
