title: Tyrosine deprotonation and associated hydrogen bond rearrangements in a photosynthetic reaction center.
abstract: Photosynthetic reaction centers from Blastochloris viridis possess Tyr-L162 located mid-way between the special pair chlorophyll (P) and the heme (heme3). While mutation of the tyrosine does not affect the kinetics of electron transfer from heme3 to P, recent time-resolved Laue diffraction studies reported displacement of Tyr-L162 in response to the formation of the photo-oxidized P(+•), implying a possible tyrosine deprotonation event. pK(a) values for Tyr-L162 were calculated using the corresponding crystal structures. Movement of deprotonated Tyr-L162 toward Thr-M185 was observed in P(+•) formation. It was associated with rearrangement of the H-bond network that proceeds to P via Thr-M185 and His-L168.
authors: Career-Path Promotion Unit for Young Life Scientists, Graduate School of Medicine, Kyoto University, Kyoto, Japan. hiro@cp.kyoto-u.ac.jp
authors: Hiroshi
authors: H
authors: Ishikita
mesh_terms: D006860:Hydrogen Bonding; D008958:Models, Molecular; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000378:metabolism*; D020560:Proteobacteria / Q000378:metabolism*; D011522:Protons; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins; D011522:Protons; D014443:Tyrosine