Phytochromobilin C15-Z,syn → C15-E,anti isomerization: concerted or stepwise?
2004 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 6, no 21, 5066-5073 p.Article in journal (Refereed) Published
The C15-Z,syn C15-E,anti isomerization of phytochromobilin that underlies the photoactivation of phytochrome, the plant photoreceptor responsive to red and far-red light, is investigated by means of quantum chemical methods. By calculating ground and excited-state potential energy surfaces for a phytochromobilin model comprising the full tetrapyrrolic skeleton, and taking into consideration rotations around the C14–C15 and C15=C16 bonds constituting the methine bridge between pyrrole rings C and D, it is found that a stepwise Z E, syn anti mechanism is energetically preferable over a concerted Z,syn E,anti mechanism. In particular, on the basis of the calculated potential energy surfaces, it is proposed that the primary photochemical reaction involves a Z E isomerization only, and that the subsequent syn anti isomerization proceeds thermally.
Place, publisher, year, edition, pages
Royal Society of Chemistry, 2004. Vol. 6, no 21, 5066-5073 p.
IdentifiersURN: urn:nbn:se:liu:diva-96777DOI: 10.1039/B411005FOAI: oai:DiVA.org:liu-96777DiVA: diva2:643325