Possession of the partial amino-acid sequence of a patented protein does not necessarily entitle the inventors to claim the DNA sequence that encodes it, according to the US Patent and Trade Office (PTO). In the case In re Wallach, the PTO rejected Wallach's claims to the DNA molecules that encode tumour-necrosis factor (TNF)-binding protein II (TBP-II), on the basis that these claims do not meet the 'written description' requirement, a ruling that was upheld recently by the US Court of Appeals.

In the 1980s, Wallach and colleagues discovered two proteins in urine that inhibit the cytotoxic effect of TNF and termed them TBP-I and -II. After obtaining a partial sequence for TBP-II, they filed an application that included claims to proteins with this partial sequence and molecular mass, as well as the DNA that encodes them. The claims to the proteins are not at issue in this case; however, the claims directed to the DNA were rejected because the applicants are only in possession of a partial amino-acid sequence and according to the PTO this does not comprise adequate written description of the claimed subject matter — that is, the DNA sequence.

Possession of the partial amino-acid sequence of a patented protein does not necessarily entitle the inventors to claim the DNA sequence that encodes it.

Wallach and colleagues appealed on the basis that the determination of the amino-acid sequence of a protein immediately puts one in possession of all DNA sequences encoding that protein. Furthermore, they argue that the complete amino-acid sequence is an inherent property of an isolated protein and that being in possession of the protein means that they were necessarily in possession of its complete sequence. However, the court ruled that although the written description requirement can in some cases be satisfied by functional description, this is only sufficient if there is a known structure-function relationship. In this case, the Appellants provided no evidence that there is any known or disclosed correlation between the combination of a partial structure of a protein, the protein's biological activity and the protein's molecular mass, on the one hand, and the structure of the DNA encoding the protein on the other.