title: Site specific inhibition by alpha-benzyl-alpha-bromomalodinitrile (BBMD) of electron transport in spinach chloroplasts.
abstract: The addition of alpha-benzyl-alpha-bromomalodinitrile to different controlled states (non-phosphorylating [2]. phosphorylating [3], ATP-inhibited [4] and uncoupled) of photosynthetic electron transport to ferricyanide or benzoquinone demonstrate a significant inhibition in isolated spinach chloroplasts. alpha-Benzyl-alpha-bromomalodinitrile pretreatement of isolated chloroplasts or addition of alpha-benzyl-alpha-bromomalodinitrile at the onset of illumination completely abolished the O2 evolving reaction. The level of the steady state fluorescence in intact chloroplasts showed a alpha-benzyl-alpha-bromomalodinitrile concentration-dependent increase. The gradual decrease in the reoxidation capacity of the reduced quencher, Q with increasing alpha-benzyl-alpha-bromomalodinitrile concentrations provides evidence for an additional inhibitory site for alpha-benzyl-alpha-bromomalodinitrile between the two photosystems.
mesh_terms: D000641:Ammonia / Q000494:pharmacology; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism*; D004579:Electron Transport; D007700:Kinetics; D009570:Nitriles / Q000494:pharmacology*; D010788:Photosynthesis / Q000187:drug effects; D010944:Plants; D013050:Spectrometry, Fluorescence; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D009570:Nitriles; D014475:Uncoupling Agents; C003892:alpha-benzyl-alpha-bromomalodinitrile; D000641:Ammonia