An amino acid mixture consisting
of arginine, glutamic
acid, and leucine is to be
separated by ion-exchange chromatography, using a cation-exchange
resin at pH 3.5, with the eluting buffer at the same pH. The first
amino acid to be eluted will be glutamic acid.
The other two amino acids will remain on the column because they
are positively charged.
In order to elute these two proteins from the column it will be
necessary to
(a) raise the pH first to 7 to
elute arginine, and then raise it to 11 to
elute leucine.
(b) lower the pH first to 4 to
elute arginine, and then raise it to 11 to
elute leucine.
(c) raise the pH first to 7 to
elute leucine, and then raise it to 11 to
elute arginine.
(d) raise the pH first to 7 to
elute arginine, and then lower it to 2 to
elute leucine.
(e) lower the pH first to 4 to
elute leucine, and then lower it to 2 to
elute arginine.