Automated Edman degradation was used to determine the amino acid sequence of the proteins as described in the N-terminal amino acid Sequence determination section. Add any key missing O. N. or H atoms and electron pushing arrows to complete the reaction mechanisms for the addition of the Edman reagent (phenyl isothiocyanate or PITC) to form the PTC derivative, the intermediate cyclic compound, and the breaking of the peptide bond to form the intermediate thiazolinone, V=O=8 HAN peptide PITC HN HN peptide PTC Derivative peptide OH HUR TIR HN HAN-peptide Cyclic Intermediate Thiazolinone intermediate PTH