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Literature summary extracted from

  • Santabarbara, S.; Bullock, B.; Rappaport, F.; Redding, K.
    Controlling electron transfer between the two cofactor chains of photosystem I by the redox state of one of their components (2015), Biophys. J., 108, 1537-1547 .
    View publication on PubMedView publication on EuropePMC

Protein Variants

EC Number Protein Variants Comment Organism
1.97.1.12 F689N site-directed mutagenesis of subunit PsaA, the mutation causes in an about 100fold decrease in the observed rate of cofactor phylloquinone PhQA- oxidation, resulting in a lifetime that exceeds that of the terminal electron donor, P700+. This situation allows a second photochemical charge separation event to be initiated before PhQA- has decayed, thereby mimicking in PSI a situation that occurs in type II reaction centers. Simulation of the pump-pump kinetics in PsaA-F689N, overview Chlamydomonas reinhardtii

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
1.97.1.12 additional information
-
 additional information kinetics of electron transfer of wild-type and mutant enzymes, overview Chlamydomonas reinhardtii

Localization

EC Number Localization Comment Organism GeneOntology No. Textmining
1.97.1.12 thylakoid
-
 Chlamydomonas reinhardtii 9579
-

Natural Substrates/ Products (Substrates)

EC Number Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
1.97.1.12 reduced plastocyanin + oxidized ferredoxin + hv Chlamydomonas reinhardtii
-
 oxidized plastocyanin + reduced ferredoxin
-
 ?
1.97.1.12 reduced plastocyanin + oxidized ferredoxin + hv Chlamydomonas reinhardtii KRC91-1A
-
 oxidized plastocyanin + reduced ferredoxin
-
 ?

Organism

EC Number Organism UniProt Comment Textmining
1.97.1.12 Chlamydomonas reinhardtii P12154 AND P09144 AND Q00914 psaA, psaB, and psaC
-
1.97.1.12 Chlamydomonas reinhardtii KRC91-1A P12154 AND P09144 AND Q00914 psaA, psaB, and psaC
-

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
1.97.1.12 reduced plastocyanin + oxidized ferredoxin + hv
-
 Chlamydomonas reinhardtii oxidized plastocyanin + reduced ferredoxin
-
 ?
1.97.1.12 reduced plastocyanin + oxidized ferredoxin + hv
-
 Chlamydomonas reinhardtii KRC91-1A oxidized plastocyanin + reduced ferredoxin
-
 ?

Synonyms

EC Number Synonyms Comment Organism
1.97.1.12 PSI
-
 Chlamydomonas reinhardtii

Cofactor

EC Number Cofactor Comment Organism Structure
1.97.1.12 phylloquinone
-
 Chlamydomonas reinhardtii

General Information

EC Number General Information Comment Organism
1.97.1.12 malfunction site-directed mutagenesis of residues involved in the respective phylloquinone-binding sites results in a specific alteration of the rates of semiquinone oxidation. Mutation in the PhQA binding pocket (PsaA-F689N) in PSI of Chlamydomonas reinhardtii reduces down PhQA- oxidation kinetics by almost two orders of magnitude. This creates an unprecedented situation in which the reduction of P700+ is faster than the oxidation of the semiquinone, thereby providing the opportunity to initiate a second photochemical event while PhQA- is still present in ETCA, kinetics, overview Chlamydomonas reinhardtii
1.97.1.12 physiological function two functional electron transfer (ET) chains, related by a pseudo-C2 symmetry, are present in the reaction center of photosystem I (PSI). Due to slight differences in the environment around the cofactors of the two branches, there are differences in both the kinetics of ET and the proportion of ET that occurs on the two branches. The oxidation rates of the reduced phylloquinone (PhQ) cofactor differ by an order of magnitudes. The presence of PhQ-A does not impact the overall quantum yield and leads to an almost complete redistribution of the fractional utilization of the two functional ET chains, in favor of the one that does not bear the charged species, molecular mechanism that gives rise to the high quantum efficiency in PSI, overview Chlamydomonas reinhardtii