Physiology/Biochemistry of Photoactivation of O sub 2 Evolution: Probes for the S-State Protein. Progress Report, June 1, 1983-May 31, 1985

摘要

This work details the conditions necessary to achieve routinely the complete photoactivation of virtually totally inactive water oxidizing complexes in NH sub 2 OH extracted leaf segments. The photoactivation process per se proved entirely similar to the process previously described for Mn deficient algae, Mn sufficient algae cultured heterotrophically, and NH sub 2 OH extracted algae. Further studies showed that without dark preincubation of NH sub 2 OH extracted leaf segments PS 2, but not PS 1, was susceptible to weak light photoinhibition (t1/2 approx. 2.5 min). Also reported are studies which kinetically characterize the photoinhibition process using NH sub 2 OH or Tris extracted isolated chloroplasts, prove the site affected resides on the oxidant side of PS 2, and give preliminary identification of the polypeptide which must be synthesized on chloroplast 70S ribosomes for the recovery from photoinhibition and for recovery of the capacity of PS 2 to carry-out photoactivation of the Mn-S-state enzyme. 25 refs., 6 figs., 1 tab. (ERA citation 10:041469)