Functional Claiming in Biotechnology

In biotechnology, it is often difficult to define an invention solely in structural terms. While nucleotide and amino acid sequences provide a precise way to identify specific molecules, they do not always capture the full range of materials that may share a useful biological activity. As a result, applicants frequently seek to define biotechnology inventions, at least in part, by what they do rather than strictly by what they are. This approach is commonly referred to as functional claiming.

Functional claims describe a biological material, such as a protein, antibody, peptide, or nucleic acid, by reference to its activity or effect, rather than its exact structure. For example, a claim may be directed to a protein that binds a particular target, a peptide that inhibits a receptor, or a nucleic acid that produces a specified biological response.

Although functional claiming can be attractive, it raises significant issues under the written description and enablement requirements. Written description focuses on whether the application demonstrates that the inventor was in possession of the claimed invention at the time of filing. Enablement asks whether the application teaches a person skilled in the art how to make and use the claimed invention without undue experimentation. In biotechnology, both requirements can be challenging when claims extend beyond the specific examples disclosed.

For example, where an applicant discloses only a single protein sequence and one associated function, the safest claims will generally be limited to that specific sequence or to very closely related variants, such as proteins differing only by conservative amino acid substitutions. Broader claims, such as those based on percent sequence identity combined with a functional limitation, may be possible, but they typically require stronger support. This may include evidence that the relevant protein family is predictable, that certain regions are conserved, that substitutions are tolerated in other regions, or that representative variants retain the claimed function. Applicants commonly present claims of varying scope, allowing broader protection to be pursued while preserving narrower fallback positions. A graduated claim set might include:

1.   An isolated protein comprising the amino acid sequence of SEQ ID NO:1.

2.   The protein of claim 1, wherein the protein has function X.

3.   An isolated protein comprising an amino acid sequence having at least 98% sequence identity to SEQ ID NO:1 and retaining function X.

4.   The protein of claim 3, wherein the sequence differs from SEQ ID NO:1 only by conservative amino acid substitutions.

5.   An isolated protein comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO:1 and retaining function X.

6.   An isolated protein comprising an amino acid sequence having at least 90% sequence identity to SEQ ID NO:1 and retaining function X.

Whether broader claims in such a set are ultimately allowed will depend on the depth of the disclosure and the predictability of the underlying technology. Nonetheless, presenting claims of graduated scope provides a structured way to test the limits of what the application can reasonably support.

Understanding functional claiming is essential when evaluating patentability in biotechnology. Ultimately, the scope of the claims must be commensurate with the scope of the disclosure.

Disclaimer: This piece is provided for general informational purposes only and does not constitute legal advice. Patent issues are often complex and highly fact-specific, and no one should act on general information of this kind without consulting qualified patent counsel regarding the particular circumstances involved.