[RASMB] another vbar question

[Rocco Mattia]

Damn the auto-emoticons... it's  H2O(sixteen) and H2O(eighteen) 
:-D

________________________________

From: RASMB on behalf of HGSR (Holger Martin Strauss)
Sent: Thu 9/28/2017 3:48 PM
To: rasmb at list.rasmb.org
Subject: [RASMB] another vbar question


Hello yall,
 
Wow, vbar trending?!
 
I actually have a question regarding the salt-dependency of the vbar. We are working with peptides modified with some organic linkers and a diacid (between C4-C50, to give a range). We measure the droh/dc (DMA5000) at different concentrations and calculate the vbar. Controls OK, concentration accurate and measurements reproducible, buffer dialysed. Salt-concentration is varied (NaCl, 5-1500 mM-ish). Turns out the vbar is considerably different at high salt. (And so is the self-association, btw.) No detergents or denaturants, just some additional phosphate for buffering, besides the NaCl.
 

	
*	How can this be rationalised structurally? 
*	Any tests when droh/dc is more appropriate for Mw /sigma than vbar? 
*	Other examples in the literature for peptides? 
*	Any general comments/anectodes/remarks? 

 
Cheers, 
 
Holger