We have investigated the previous suggestions in the literature that the outer antenna of Photosystem II of barley does not influence the effective photosystem primary photochemical trapping rate. It is shown by steady state fluorescence measurements at the F0 fluorescence level of wild type and the chlorina f2 mutant, using the chlorophyll b fluorescence as a marker, that the outer antenna is thermally equilibrated with the core pigments, at room temperature, under conditions of photochemical trapping. This is in contrast with the conclusions of the earlier studies in which it was suggested that energy was transferred rapidly and irreversibly from the outer antenna to the Photosystem II core. Furthermore, the effective trapping time, determined by single photon counting, time-resolved measurements, was shown to increase from 0.17±0.017 ns in the chlorina Photosystem II core to a value within the range 0.42±0.036-0.47±0.044 ns for the wild-type Photosystem II with the outer antenna system. This 2.5-2.8-fold increase in the effective trapping time is, however, significantly less than that expected for a thermalised system. The data can be explained in terms of the outer antenna increasing the primary charge separation rate by about 50%.
The effect of outer antenna complexes on the photochemical trapping rate in barley thylakoid Photosystem II / E.C. M Engelmann, G. Zucchelli, F.M. Garlaschi, A.P. Casazza, R.C. Jennings. - In: BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS. - ISSN 0005-2728. - 1706:3(2005), pp. 276-286.
|Titolo:||The effect of outer antenna complexes on the photochemical trapping rate in barley thylakoid Photosystem II|
ENGELMANN, ENRICO CLETO MARIA (Primo)
CASAZZA, ANNA PAOLA (Penultimo)
JENNINGS, ROBERT CHARLES (Ultimo)
|Parole Chiave:||antenna effect; chlorina f2; Photosystem II; thylakoid; trapping time|
|Settore Scientifico Disciplinare:||Settore BIO/04 - Fisiologia Vegetale|
|Data di pubblicazione:||2005|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1016/j.bbabio.2004.11.009|
|Appare nelle tipologie:||01 - Articolo su periodico|