osmoregulation and proline

adwright at iastate.edu adwright at iastate.edu
Wed Nov 17 10:50:45 EST 1993

In <CGLqJK.CDD at acsu.buffalo.edu> v052lttb at ubvms.cc.buffalo.edu (Gandalf the Grey) writes:

>	 Next week I will be giving a talk on the many roles of Abscisic 
>Acid on plant growth and development.  One of the central themes in which 
>ABA is associated with is osmotic stress.  In the review acticles and the 
>texts I have read mention that proline is an important osmoprotectant, but 
>I can't find out why.  Can anyone help me out with a simple explanation??
>I must admit I won't be covering this in my talk, it is more for personal 
>interest.  Any input would greatly be appreciated.
>		Thanks,
>	Joe Boinski
>	SUNY at Buffalo  

I think that most researchers agree that, at the concentrations generally
 found in plants under stress, proline does not make a great
contributuin to the osmotic potential per se of a plant cell.

There is a lot of literature debating the role of proline accumulation in
higher plants. Articles by Andrew Hanson, Barnet and Naylor, and Cecil
Stewart are worth looking for. 

 Another interesting article (sorry, dont have the reference)  was written
by Schobert and Tschese (not sure of the second author's spelling) which
describes the "unusual" soultion properties of proline.  The hydrophobic
part of the molecule attracts each other, causing it to behave like a
very small micelle in aqueous solutions.  Furthermore, the attraction of
the hydrophobic part of proline to hydrophobic amino acid side chains
will effectively increase the hydrophilic surface area of the protein.
The result is that proteins in a solution containing proline will be more
difficult to "salt out" of soultion. If the protein happens to be an enzyme,
the activity will be retained at a higher salt concentration.



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