(just in fun - this is not really my topic!)
In article <1995Jan27.024118.3087 at alw.nih.gov>, rvenable at deimos.cber.nih.gov (Rick Venable) writes:
> On Thu, 26 Jan 1995 22:53:19 GMT Mohan Srinivasan pontificated:
>> Can proteins fold in a different way in the absence of
>> gravity ? I believe that their density changes (compacts) when
>> spun in ultracentrifuges at high rpm's (high G). So, the reverse
>> (low G) should be also true. Gravity is one of the forces apart
>> from the nuclear forces. Does folding depend only on nuclear
>> forces ? I am not sure though. Was any study made in this direction
>> during space experiments ? Could anyone throw some light ?
>> I'd say that there is little or no difference. First, the difference
> between 0 G and 1 G is very small, compared to the high G force in a
> modern ultracentrifuge. Second, perhaps many astronauts would be dead if
> the change from 1 G to 0 G seriously altered protein folding.
Nicely put.
> Third, most
> theoretical chemistry programs (molecular dynamics, quantum calculations,
> etc.) ignore gravity completely. Not that the absence is proof, but many
> leading scientists studying protein folding from a theoretical approach do
> not consider gravity. After all, the mass of a protein is infintesimal
> compared to the mass of the Earth, and it exists in a buoyant medium.
>[snip]
Just another thought - do proteins care "which way up" they are while they
are folding - I doubt it! (a grativational effect implies a directional
effect).
Grant.
