From: Jeffrey A. Cohlberg <cohlberg@csulb.edu>
  To  : rasmb@bbri.org
  Date: Fri, 25 Jun 1999 14:34:43 -0700

Re: charge effects

Walter Stafford wrote:
> 
> Hi RASMBers
> 
>         For those who are performing sedimentation experiments in water or
> very low ionic strength buffer, you might want to consult Howard Schachman's
> book "Ultracentrifugation in Biochemistry" Academic Press 1959 pp225- for a
> discusion of the effect of charge on the apparent molecular weight. See
> especially equation 133 which gives the limiting value in the absence of
> supporting electrolyte. See also T.Svedberg and K.O Pederson "The
> Ultracentrifuge" Oxford Uinversity Press, 1940. pp53 and 54 in which they give
> relations for multivalent (eqn 99) and univalent (next unnumbered eqn)
> counterions. The limiting relation for high ionic strength is given in eqn
> 101.

Another relevant reference might be Johnson and Yphantis (1978)
Biochemistry 17, 1448-1455, which details a method for calculating a
correction for charge effects.

Jeff Cohlberg

-- 
Jeffrey A. Cohlberg, Professor
Department of Chemistry and Biochemistry
California State University, Long Beach
1250 Bellflower Blvd.
Long Beach, CA 90840
phone (562) 985-4944	  fax (209) 821-4471