(Halford Dace) writes:
>>I have recently been doing some reading about chloroplast antioxidant
>mechanisms and am uncertain about some aspects of the generally
>accepted results of fluoresecence measurements.
>>Reviews such as [1] and [2] listed below describe two types of fluorescence
>quenching:
>>Qp (Photochemical quenching) which I understand as the quenching due to
>normal operation of the electron transport chain (ie reduction & reoxidation
>of Qa)
(should be qP)
>Qnp (nonphotochemical quenching) which they attribute largely to a quantity
>termed Qe (energy-dependant quenching), described as a transmembrane
>delta-pH dependent quenching. In other words, as the thylakoid lumen [H+]
>increases, flourescence drops for reasons which I'm not clear about.
Should be "qN" - the terminology was revised in 1990, but people are still
not consistent in their usage.
qE is due to energy dissipation in the light harvesting apparatus, induced
by the delta-pH. The most recent review is
"Regulation of Light Harvesting in Green Plants"
Horton P, Ruban AV, Walters RG (1994), Plant Physiol 106:415-420
Robin Walters, Robert Hill Institute, Sheffield UK
Scientists for Labour R.G.Walters at shef.ac.ukhttp://www.shef.ac.uk/uni/projects/sfl/index.htmlmbrgw at seqnet.dl.ac.uk
