Question

A mixture of amino acids (Arg, Asp, Leu, Asn, Pro, Ser) is subject to paper chromatography in an acetic acid-butanol-water mixture (non-polar solvent) at pH 3.5. The paper is then turned 90 degrees and paper electrophoresis is carried out at a pH of 9. Draw the 2D chromatograph and where each amino acid would fall.

Answer 1

The three solvents you are using have a polar behavoir, and the acetic acid is releasing H+, thu the pH is low.

The more polar amino-acids are the ones that moving farther, Arg has three amino compounds and also it is fully positive charged so it is the first, Asp has a very polar carboxylic acid and it is fully deprotonated (pKa 2.7) so it is just behind. Asn has a a amide gruop very polar, Ser has an -OH a little bit less polar, Pr non-polar with three carbons in a ring, and finally the Leu without any polar group.