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 |
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 |
EC Number | Localization | Comment | Organism | GeneOntology No. | Textmining |
---|---|---|---|---|---|
1.97.1.12 | thylakoid | - |
Chlamydomonas reinhardtii | 9579 | - |
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 | - |
? |
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 | - |
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 | - |
? |
EC Number | Synonyms | Comment | Organism |
---|---|---|---|
1.97.1.12 | PSI | - |
Chlamydomonas reinhardtii |
EC Number | Cofactor | Comment | Organism | Structure |
---|---|---|---|---|
1.97.1.12 | phylloquinone | - |
Chlamydomonas reinhardtii |
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 |