What amino acids are considered “specifically defined” according to WIPO Standard ST.26?

MPEP 2412.03(a) refers to WIPO Standard ST.26, which defines “specifically defined” amino acids as any amino acid other than those represented by the symbol “X”. The MPEP provides a table of amino acid symbols, where:

• Single-letter symbols A, R, N, D, C, Q, E, G, H, I, L, K, M, F, P, O, S, U, T, W, Y, and V represent specifically defined amino acids
• Symbols B, Z, and J represent combinations of specifically defined amino acids
• The symbol X represents “unknown” or “other” and is not considered specifically defined

This definition is important for patent applications filed on or after July 1, 2022, containing amino acid sequence disclosures.

To learn more:

• amino acid sequences
• WIPO Standard ST.26
• patent applications
• specifically defined amino acids