Our instrument can readily sequence 10 pmole of standard protein, but we suggest supplying more sample if it is readily available, because sample losses during handling often reduce the amount we receive from what people estimate. The length of sequence obtained may be limited by sample amount, but is always limited by the properties of the protein. Side reactions increase the background of amino acids and decrease the amount of amino acid released from the protein. Large proteins give more background signal than smaller proteins. Our best run was about fifty amino acids.
Edman chemistry can identify radiolabelled phosphorylation sites in peptides.
Other modified amino acids may not be identified but their presence inferred by the lack of data. Cysteine cannot be positively identified unless it is alkylated. Available is a document with a description of sample preparation methods including many references and an explanation of the process of protein sequencing. When submitting a sample, please include a sample submission form . Sample preparation for Edman sequencing more demanding than for MS Mass analysis of peptides and proteins The W.M Keck Biomedical Mass Spectrometry Laboratorycan accurately determine the mass of peptides and proteins.