How should modified bases or amino acids be represented in a Sequence Listing?

According to MPEP 2423.01, modified bases or amino acids should be represented in a Sequence Listing as follows:

1. If the modified base or amino acid is listed in Appendices B and D to Subpart G of Part 1 of the CFR, it can be presented as the corresponding unmodified base or amino acid in the main sequence.
2. The modification must be set forth in the Feature section of the Sequence Listing.
3. If the modified base or amino acid is not listed in Appendices A and C, it must be listed as “n” for nucleotides or “Xaa” for amino acids in the main sequence.
4. Additional information about the modification should be provided in the Feature section using feature keys listed in Appendices E and F.

The MPEP states: “Otherwise, all nucleotide bases or amino acids not appearing in Appendices A and C to Subpart G of Part 1 of the CFR must be listed in a given sequence as ‘n’ or ‘Xaa,’ respectively, with further information given in the Feature section of the ‘Sequence Listing’ by including one or more feature keys listed in Appendices E and F to Subpart G of Part 1 of the CFR.”

To learn more:

• Sequence Listing
• modified bases
• modified amino acids
• biotechnology patents
• patent application