Thin-layer peptide mapping: Quantitative analysis and sequencing at the nanomole level

Peptides separated by chromatography and electrophoresis on thin layers of silica gel G were scraped off and hydrolyzed without prior removal of the silica. The complete amino acid composition, including tryptophan content, was obtained for each peptide. Contaminating amino acids were in sufficiently low concentrations that accurate quantitation of less than 1 nmol was possible. Peptides were eluted from the silica in high yield providing material suitable for sequence determination. This method provides a rapid quantitative procedure that can be used to screen for protein variants and/or purify nanomole levels of peptides for primary structure studies.