Re: Poly-Ala

[shenkin ( ( at ) ) avogadro.barnard.columbia.edu (Peter S. Shenkin)]

 Gee, a real SCIENCE discussion on this list!  I love it!
 Shaun D. Black          | Bitnet: black ( ( at ) ) ohstphrm.bitnet writes:
 > It is my recollection that poly-Ala is only sparingly soluble in water,
 > but enough can be gotten into solution to do a CD spectrum and see that it
 > is alpha helical.  Poly-Gly will probably be more soluble in water, but
 > only because it likely unfolds and hydrogen bonds with the solvent.  My
 > bet is for "random coil" in water.  It's not clear to me what the
 entropic
 > considerations would be, net....
 In aqueous solution entropic changes in the solvent are important.  I'm almost
 sure poly-ALA is helical in CCl4.  If poly-GLY is a random coil in that
 solvent, my guess is that its greater chain entropy (greater allowed region in
 the Ramachandran plot is responsible).  I admit that this is a supposition on
 top of a supposition, so maybe someone out there who knows can comment.
 >                           ....More discussion on this would be interesting.
 Always glad to add my $.02    :-)
 	-P.
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 Peter S. Shenkin, Department of Chemistry, Barnard College, New York, NY 10027
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