[Myotox] SDS AUC update

[Bruno Lomonte]

Dear colleagues


thanks for running these new experiments, and finding such interesting 
results!


so this dimerization induced by SDS would explain the appearance of a 
smear around the dimeric value in such electrophoretic analyses?   and 
this would support that under physiological conditions the toxin would 
be a monomer, the dimer being an artifact of crystallization perhaps? I 
am not sure if I am interpreting this correctly


exciting news indeed


very best regards and thank you so much


Bruno




PS: it is likely that I will have an important surgery in the next days, 
which might keep me a bit disconnected for few weeks, in case you do not 
see me replying quickly to mails



+++++




On 3/12/2020 4:52 PM, Henrickson, Amy wrote:
> Hello,
>
> Just to clarify the SDS concentration was 1%(w/v).
>
> Cheers,
> Amy Henrickson
> ------------------------------------------------------------------------
> *From:* Myotox <myotox-bounces at biophysics.uleth.ca> on behalf of 
> Borries Demeler <demeler at gmail.com>
> *Sent:* Thursday, March 12, 2020 2:45 PM
> *To:* myotox at biophysics.uleth.ca <myotox at biophysics.uleth.ca>
> *Subject:* [Myotox] SDS AUC update
> Dear all,
> Amy ran the most recent samples from Bruno in the presence of 1 mg/ml
> SDS at two protein concentrations (1 mg/ml and 0.17 mg/ml). The results
> are quite consistent with the results in Susumu's paper. We do see
> oligomerization, with a more or less final state. At this point I am not
> clear if it is a dimer or trimer or something higher, this still needs
> to be determined. But it is very clear that SDS has a big effect on
> dimerization. What also is interesting is that the association behavior
> induced by SDS appears to be reversible. That is, you get dissociation
> of the oligomer in response to lowering the concentration. We will
> further test this by using even lower concentration to see if we can
> shift to entirely monomer. We will also do D2O density matching to see
> if there is a density difference between monomer and dimer and
> potentially higher oligomers due to different ratios of SDS binding to
> myotoxin-II.
>
> Now we need to come up with a strutural explanation why this
> oligomerization shift is happening in response to addition of SDS. I
> would also like to know if some other lipids could cause the same effect
> as a detergent? A figure is attached that shows the sedimentation
> distribution, it looks like similar values as those obtained for the
> different toxin in the Uchiyama paper.
>
> Regards, -Borries
>
>
>
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-- 
Bruno Lomonte, Ph.D.
Instituto Clodomiro Picado
Universidad de Costa Rica
San José, 11501
COSTA RICA

bruno.lomonte at ucr.ac.cr
tel. +506  2511 7888
cel. +506  8392 0012

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