Determination of N-terminal sequence of elgicin B using standard Edman degradation method. A, The 20 known amino acids served as standards. The peak representing the cysteine residue was not labeled. B-E, The first four amino acids in the N-terminal region of elgicin B (leucine, glycine, asparagine, and tyrosine) were determined. Diphenylthiourea (dptu) is the by-product of the Edman degradation reaction.