Turn distance monitor on, or off, or clear current distances. (To measure distance, click with left mouse-button on one atom, then another. If in stereo view, use right image). The chromophores Chlorophylls (Chl) of the "special pair" (green), and the ancillary pair (greenblue), pheophytins (Ph) (magenta), "connecting" chlorophylls (blue), plastoquinones (QA, yellow; QB, not present), Fe (red). The Mn-cluster involved in oxygen evolution is shown in cyan. Only one monomer is colored. The protein The protein added as a backbone model. In one monomer, D1 is shown in blue; D2 in green; cyt b-559 in orange. The donor side Stop the rotation before going on Zoom in on the Mn-cluster, and show the two redox-active tyrosines. ©Copyright 1996, Antony Crofts, University of Illinois at Urbana-Champaign, a-crofts@uiuc.edu