What is the purity for the crude peptide and the desalted peptide? How do you purify the peptide? What are the impurities?
For short peptides with normal sequences under 15aa, it is generally 40-60% by HPLC for crude grade; 50-70% by HPLC for desalted grade. The longer peptide is, the lower purity is for crude or desalted. Peptides are generally purified by HPLC using water and acetonitrile gradient. Most impurities are incorrectly synthesized peptides, such as fragments or deletion peptides, incompletely de-protected peptides and residual water.
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05/08/2013