Kinetics and Energetics of Phylloquinone Reduction in Photosystem I: Insight From Modeling of the Site Directed Mutants.

ABSTRACT: Two phylloquinone molecules (A ₁), one being predominantly coordinated by PsaA subunit residues (A _1A) the other by those of PsaB (A _1B), act as intermediates in the two parallel electron transfer chains of Photosystem I. The oxidation kinetics of the two phyllosemiquinones by the iron-sulfur cluster F_X differ by approximately one order of magnitude, with A 1 A - being oxidized in about 200 ns and A 1 B - in about 20 ns. These differences are generally explained in terms of asymmetries in the driving force for F_X reduction on the two electron transfer chains. Site directed mutations of conserved amino acids composing the A ₁ binding site have been engineered on both reaction center subunit

SUBMITTER: Santabarbara S 

PROVIDER: S-EPMC6614487 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature