[RASMB] pressure induced dissociation

[Jack Kornblatt]

I have not been following the conversation very carefully but the 
question of whether centrifugation induced pressure changes should cause 
dissociation of multisubunit biological structures is of general 
interest. Back in 1986, Pande and Wishnia (J.Biol.Chem. 261, 6272) were 
studying the dissociation of intact ribosomes using hydrostatic pressure 
as the perturbant. Their findings are interesting. Delta V of 
dissociation for the E. coli ribosome is -240 mL/mol. The initial Kd is 
dependent on the Mg(2+) concentration but Delta V is not.
This means that if you set the initial [Mg] at the correct value, 
dissociation occurs at pressures well below 1000 atm and as low as 300 
atm. The latter pressure is easily reached in the AUC.
It also means that if our ribosomes were similarly sensitive, those 
which were sandwiched between the long bones of the leg would undergo 
dissociation every time we went for a run or even a good walk!
Your knees thank their lucky stars that our ribosomes are somewhat more 
hardy even if Infante and Baierlein thought that the urchin ribosome was 
  more sensitive still.
best regards
jack (kornblatt)


smcbryan wrote:
> All, 
> Would anyone/everyone care to comment on these results:
> http://www.ncbi.nlm.nih.gov/pmc/articles/PMC389292/pdf/pnas00083-0121.pdf
> and perhaps generalize on how/if they present a common or uncommon
> phenomenon in centrifugation. 
> Is this something that we should look out for, or is it very specific to
> this particular complex?
> thanks, 
> steve
>