Reagents and methods for the digital analysis of proteins or peptides are provided. Specifically provided herein are proteins for identifying the N-terminal amino acid or N-terminal phosphorylated amino acid of a polypeptide. Also, an enzyme for use in the cleavage step of the Edman degradation reaction and a method for using this enzyme are described.

Reagents and methods for the digital analysis of proteins or peptides are provided. Specifically provided herein are proteins for identifying the N-terminal amino acid or N-terminal phosphorylated amino acid of a polypeptide. Also, an enzyme for use in the cleavage step of the Edman degradation reaction and a method for using this enzyme are described.