In article <D9I42K.KJL at cyf-kr.edu.pl>, ubziobro at jetta (Rafal Ziobro) wrote:
> I have recently measured some spectra of thylakoids suspension
> ascorbate reduced- ferricyanide oxidized. As I know cytochrome f
> should have a maximum at 554 nm, but my results are slightly different.
> The maximum is shifted about 3-4 nm to higher wavelenghts.
> Is there a reasonable explanation of this fact?
> I would appreciate any suggestion (maybe this are some ascorbate
> reducable thylakoid components visible in that region which I do not know).
> Thanks in advance
It sounds like you're observing the spectrum of cyt b-559 there. b6 isn't
reduced by ascorbate. reduced b-559 has absorption maxima at 559, 530 and
429 nm (at room temp). It may be worth checking the wavelength calibration
of your monochromator too ;) Cytochrome b3 also has an alpha band at 559
nm and is ascorbate reducible, although it's very unlikely to be in your
thylakoid suspension. b3 is a curious protein and very little is known
about it. It's
water soluble and doesn't appear to be located in the chloroplast and so
is unlikely to present in your sample.