1.
FEBS Lett
; 250(2): 271-4, 1989 Jul 03.
Article
in English
| MEDLINE
| ID: mdl-2546799
ABSTRACT
Photosystem I preparations were irradiated with UV to destroy vitamin K1 in situ. The depletion of vitamin K1 resulted in inactivation of NADP+ photoreduction and introduction of a approximately 220 ms component in the flash generated P700+ rereduction at room temperature. The photoreduction of the terminal FeS centers FA and FB in control and vitamin K1-depleted preparations at 7 K were comparable. The data confirm that vitamin K1 is functionally implicated in primary electron transfer reactions in PS I at physiological temperature, and that the anomalous results at cryogenic temperature may be explicable in terms of a by-pass of the vitamin K1 acceptor site or heterogeneity introduced into the photosystem by quinone removal.