Lumazimes as Coenzymes in Flavodoxin : Evidence for the Occurrence of Lumazine Semiquinones

Harzer, Gerd; Ghisla, Sandro

Lumazimes as Coenzymes in Flavodoxin : Evidence for the Occurrence of Lumazine Semiquinones

Files

Lumazines_as_Coenzymes_in_Flavodoxin.pdf(267 KB)

Date

1979

Authors

Harzer, Gerd

Ghisla, Sandro

Publication type

Contribution to a conference collection

Published in

Chemistry and Biology of Pteridines : International Symposium Proceedings. - Amsterdam : Elsevier, 1979. - pp. 37-42

Abstract

6,7-Dimethyl-N(8)-ribityllumazine-5'-phosphate 1, and 6,7-{2,3-dimethylbutano)-N (8)-ribityllumazine-5'-phosphate 2, bind tightly to apoflavodoxin from Megasphera elsdenii. The complexes are reduced by 0.5 equivalents of dithionite to form the corresponding semiquinones (λmax ~ 460 - 475 nm). An enzyme bound dihydrolumazine species cannot be obtained by direct reduction of the oxidized complexes; 7,8-dihydrolumazine is modified upon binding to apoflavodoxin (λmax ~ 400 nm) suggesting formation of a different tautomer, possibly the S,8-dihydro form. The apoflavodoxin complexes of 1 and 2 show a catalytic activity, ~ 30% and ~ 90% that of the native enzyme in the photosynthetic NADP reduction of spinach chloroplasts. This allows the deduction that electron transfer in flavodoxins does not occur simply via the flavin C(8) position.

Subject (DDC)

570 Biosciences, Biology

Cite This

ISO 690

HARZER, Gerd, Sandro GHISLA, 1979. Lumazimes as Coenzymes in Flavodoxin : Evidence for the Occurrence of Lumazine Semiquinones. In: Chemistry and Biology of Pteridines : International Symposium Proceedings. Amsterdam:Elsevier, pp. 37-42

BibTex

@inproceedings{Harzer1979Lumaz-8397,
  year={1979},
  title={Lumazimes as Coenzymes in Flavodoxin : Evidence for the Occurrence of Lumazine Semiquinones},
  publisher={Elsevier},
  address={Amsterdam},
  booktitle={Chemistry and Biology of Pteridines : International Symposium Proceedings},
  pages={37--42},
  author={Harzer, Gerd and Ghisla, Sandro}
}

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