DOES GRAVITY AFFECT PROTEIN FOLDING ?

John Kuszewski johnk at spasm.niddk.nih.gov
Fri Jan 27 11:32:28 EST 1995


In article <Pine.SGI.3.91.950126174410.2174A-100000 at helix.nih.gov>, Mohan Srinivasan <smohan at helix.nih.gov> writes:
|> 
|> Hi All-
|> 
|> 	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 ?
|> 
|> Mohan Srinivasan Ph.D                            | email: smohan at helix.nih.gov 
|> DCBDC/NCI/Bldg 37 Rm 2B10,NIH,9000 Rockville Pike| phone: 301 496 2202
|> Bethesda, MD 20892, USA                          | fax  : 301 402 1031
|> 
|> 
|> 

Just to add yet another NIH voice to this--

The magnitude of gravitational forces is extremely small compared to 
the magnitude of electrostatic forces.  That's why a kitchen magnet
can hold a note to the fridge with the entire gravitational force
of the Earth pulling against it.

Of course, electrostatics (salt bridges, Hbonds, vdW, etc.) do not
determine folding by themselves--entropic considerations are nearly 
equal.  The free energy of stabilization of most folded proteins' 
structure is typically 20 kcal/mol at 25C, but the aggregate size of
the electrostatic forces holding the folded structure together is
on the order of thousands of kcal/mol.  Entropy nearly balances 
electrostatics.

And yes, some protein crystals have been grown on the Shuttle, 
but they're usually so fragile that they're unusable.
-- 
                                   _____________
                                   |        ___/_
                                   |        |/  /
                                   --  /\  //  /--
                                   ||  ||  /  /||
                                   ||  || /  / ||
                                   ||  ||/  /  ||
John Kuszewski                     ||  |/  /|  ||      
johnk at spasm.niddk.nih.gov          ||  /  /||  ||
                                   \/ /  / ||  \/
that's MISTER protein G to you!     |/__/|      |
                                      /_________|



More information about the Molmodel mailing list