questions about proteins 1
1.Explain how you would isolate a mixture of Ala-Arg-Glu using a negatively charged resin (carboxylmethyl cellulose) and a positively charged resin (DEAE).
2.A sample of a peptide of unknown sequence was treated with trypsin; another sample of the same peptide was treated with chymotrypsin. The sequences (N-terminal to C-terminal) of the smaller peptides produced by trypsin digestion were
Met—Val—Ser—Thr—Lys
Val—Ile—Trp—Thr—Leu—Met—Ile
Leu—Phe—Asn—Glu—Ser—Arg
The sequences of the smaller peptides produced by chymotrypsin digestion were
Asn—Glu—Ser—Arg—Val—Ile—Trp
Thr—Leu—Met—Ile
Met—Val—Ser—Thr—Lys—Leu—Phe
Deduce the sequence of the original peptide.
3.Explain size exclusion chromatography.
4.Explain gel isoelectric gel electrophoresis. How does it relate to pI?