Partial
resolution of the enzymes catalysing photophosphorylation
IV. Interaction of coupling factor I from chloroplast with
components of the chloroplast membrane
Bennun, A. and Racker, E.
1. A DEAE-Sephadex
chromatography step was introduced in the purification of
the latent ATPase from chloroplasts (chloroplast coupling
factor (CF1)). On elution an inactive protein was obtained,
which was reactivated on storage in 2.0 M ammonium sulfate
containing 2 mM ATP.
2. Treatment of tritium-labeled acetyl-CF1 with trypsin or
heat activated the Ca++-dependent ATPase, but abolished the
capacity of CF1 to combine with resolved chloroplast particles.
3. It was shown with tritium-labeled CF1 that a divalent cation
such as Mg++ or Ca++ was required for the binding of the protein
to the chloroplast membrane.
4. Combination of CF1 with the chloroplast membrane resulted
in an increase in the cold stability of the protein. This
allotopic property was used as an additional assay for the
Interaction between CF1 and the membrane.
5. On extraction of chloroplasts with solvents, two frac¬tions,
one soluble and one insoluble, were separated. Both were required
for the reconstitution of particles that were capable of combining
with CF1.
The Journal of Biological Chemistry, 244, (1969), 1325-1331