info on cytochrome f

Douglas C Pearson dopearso at magnus.acs.ohio-state.edu
Sun Jun 11 16:09:49 EST 1995


prof s n datta <sndatta at powai.cc.iitb.ernet.in> wrote:
>Would you please give me some information regarding the X-ray
>crystal structure of cytochrome f/cytochrome b whcich are
>involved in photosynthetic electron transfer chain?

i find it rather remarkable that i let this one sit for a week and
no one more knowledgeable than i has come forward to answer it.
if i'm the photosynthesis mailing list's resident cytochrome f
expert, i'm REALLY scared.  (bill cramer, where are you when i need
you?)

anyway, the crystal structure was solved sometime in '92/'93 by
recent PhD holder sergio martinez with bill cramer and janet smith
at purdue university.  the structure report was published in the
journal _structure_  (vol 2, p. 95, and if i remembered all that
correctly, i'll be amazed) and details have been presented at
midwest photosynthesis meeting and at biophysical society, and
that's just what i've seen myself.

basically, if you ever had any notion of what cyt f looks like that
was based at looking of pictures of the cyt c crystal structure,
throw those out the window.  cyt f is a beta-barrel protein of two
soluble domains with an alpha-helical tail (forgive my non-technical
terminology, a protein biochemist i ain't) which probably spans the 
thylakoid membrane.  the heme is partially on the protein's surface, 
with the porphyrin carboxyls exposed.  the traditional cytochrome 
CXXCH pocket is there, but the sixth ligand of the iron is the N-
terminus and not methionine, which i personally find quite wild.
there is a internal chain of six water molecules entering cyt f
around the junction between the two domains and tracking around to
a residue (can't remember which one, gotta go look up my biophysical
society notes) next to the heme.

the protein data bank code for cyt f is 1CTM.

and stay tuned for results on electrostatic properties of cyt f...

chuck pearson, mad biophysicist.
-- 
chuck pearson - dopearso at magnus.acs.ohio-state.edu
osu biophysics program, bio113 head ta, daddy of amelia catherine pearson.



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