The Patent Office provides clarity regarding enablement of polypeptide claims


Australia has relatively recently implemented support laws that require a specification to provide sufficient information to enable the skilled person to perform an invention over the entire scope of the claims without undue burden or the need for further invention. These new support laws have been stringently applied by the Patent Office, in particular in relation to claims defining chemical compounds, such as proteins where, in many cases, the only claims considered to be enabled are ones directed to embodiments exemplified in the specification.

In Evolva SA [2017] APO 57 (14 November 2017) the Patent Office considered the enablement of claims directed to polypeptide sequences covered by at least 90% sequence identity to defined polypeptide sequences.


Patent Application 2012342114 covers methods and materials for the synthesis of low calorie naturally-occurring sweeteners. Specifically, the sweeteners include glycosylated mogroside compounds produced by methods involving glycosylating enzymes, uridine-5’-diphospho dependent glucosyltransferases (UGTs).

Claim 1 defines a method of producing a mogroside compound, using a UGT polypeptide having at least 90% sequence identity to one of five specific sequences. During prosecution, the Examiner found that it was not reasonable that every single peptide covered by claim 1 would exhibit transferase activity. Moreover, the Examiner also asserted that the skilled person would be required to produce every single peptide covered by the claim and then conduct an assay on each to determine which exhibited the desired activity. This was considered to amount to an undue burden. For these reasons, the claims were rejected for lack of enablement.

Issues and findings

In determining whether the claims were enabled, and in particular claims to polypeptides having at least 90% identity to the defined sequences, the Delegate of the Patent Office considered the Explanatory Memorandum to the relevant support legislation as well as European and UK case law. Based on this, the Delegate settled on a two-step enquiry consistent with that taken under UK law[1].

The first stage involved determining whether the disclosure of the patent, read in the light of the common general knowledge of the skilled person, makes it plausible that the invention will work across the scope of the claim. If so, the second stage required consideration of whether the invention can be performed across the scope of the claim without undue burden.


The specific issue considered by the Delegate was whether it was plausible that polypeptides which have as low as 90% identity would exhibit functional activity. According to the relevant European case law, the Delegate found that the requirement of plausibility is a low threshold test where in certain cases a “plausible” or “reasonably credible” claimed use, or an “educated guess”, can suffice[2]. Notwithstanding the focus on European case law, the Delegate emphasised that the fact that near identical claims had been accepted in Europe was of little assistance and that merely referring to the outcome of corresponding overseas prosecution will not discharge the onus on the Applicant to demonstrate enablement of the Australian claims.

In coming to a conclusion regarding the plausibility of the claims, the Delegate referred to a discussion in the specification regarding the manner in which functional UGT homologues may be generated. He also referred to the fact that conservative substitution of amino acids in polypeptides is widely practiced, and that the properties of the resulting variants can be predicted with some certainty, particularly where the active binding regions of the proteins are known, which was true for the relevant UGTs. For these reasons, the Delegate found it plausible that the invention could be worked across the full scope of the claims.

Undue burden

In reaching a conclusion on the undue burden part of the enablement test, the Delegate found that the specification provided adequate guidance as to the manner in which UGT variants may be generated and tested; and that this did not present any apparent difficulties that would require the skilled person to undertake any prolonged research or experimentation that would be considered an undue effort. While the work to produce UGT variants could involve a reasonable degree of experimentation or trial and error, and even be time-consuming, the Delegate found that the nature of the work did not appear to constitute a research programme. Accordingly, the specification was found to meet the relevant enablement requirements.


This decision provides much-needed clarity regarding the test for determining enablement of chemical/protein and polypeptide claims and permits Examiners greater latitude for allowing claims directed to subject matter that goes beyond embodiments exemplified in the specification.

[1] Eli Lilly v Janssen [2013] EWHC1737

[2] Human Genome Sciences v Eli Lilly, [2012] RPC 6 

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