Hi,
To quote you: "even my P222 experimental envelop does have a 4-fold
axis" - this is not suprising, a particle with 222 symmetry does not
have 4-fold symmetry. There are 3 mutually perpendicular 2-fold axes
that intersect at the origin (of the "particle", of the molecule) [and
for the nomenclature, these axes are named the P Q and R axes].
Fred.
Fred wrote:
Thanks all of you who promptly replied my question.
I should have been more precise. I was referring to the symmetry of
the tetrameric particle (point symmetry) at the molecular level not at
the atomic level. This question has arisen because I have collected
some SAXS data of my protein in solution and I don't have a molecular
model to superpose to the experimental envelop. Others experimental
data, gel filtration and NAT-PAGE, suggest a tetrameric particle. On
the other side, P1, P2, P222 and P4 experimental envelops are quite
different. So, I am not sure which symmetry to take. Considering the
native state (no ligands at all), 4 identical subunits and that the
interface of oligomarization have to be conserved, I would take P222
or P4. However, I can be able to imagine such spacial arrangement
without a 4-fold axis at the molecular level. Indeed, even my P222
experimental envelop does have a 4-fold axis.
I appreciate if you could add some more comments on this.
Thanks in advance,
Fred
