Key cofactors of Photosystem II cores from four organisms identified by 1.7-K absorption, CD and MCD
Active Photosystem II (PS II) cores were prepared from spinach, pea, Synechocystis PCC 6803, and Thermosynechococcus vulcanus, the latter of which has been structurally determined [Kamiya and Shen (2003) Proc Natl Acad Sci USA 100: 98-103]. Electrochromic shifts resulting from Q(A) reduction by 1.7-K illumination were recorded, and the Q(x) and Q(y) absorption bands of the redox-active pheophytin