How are L-amino acids and D-amino acids treated in patent applications?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

According to MPEP 2412.03(b), both L-amino acids and D-amino acids are included in the definition of “amino acid” for patent applications. The MPEP states:

“Amino acids will be construed as unmodified L-amino acids unless further described in a feature table.”

This means that:

• L-amino acids are the default assumption and do not require special notation.
• D-amino acids must be explicitly described in the feature table to differentiate them from L-amino acids.
• Both forms are considered valid amino acids for the purposes of patent applications and sequence listings.