There’s been another big twist in the biobutanol battle between BP-DuPont joint venture Butamax and Gevo, its arch rival in advanced biofuels.
A previous post discussed the district court’s ruling granting Gevo’s motion for summary judgment of non-infringement under the doctrine of equivalents of two Butamax patents – U.S. Patent Nos. 7,993,889 (’889 Patent) and 7,851,188 (’188 Patent). The district also denied both parties’ motions on literal infringement and reached split decisions on validity of the patents.
Butamax appealed, and the Court of Appeals for the Federal Circuit recently vacated both the grant of Gevo’s motion for summary judgement of non-infringement and the denial of Butamax’s motion for summary judgment.
The ’889 and ’188 Patents are both entitled “Fermentive production of four carbon alcohols” and directed to a more cost efficient method of producing isobutanol directly from pyruvate via a particular production pathway using recombinant microbial host cells.
The patented processes use an enzyme called KARI, which needs a cofactor that donates electrons to enable it to catalyze a reaction. Based on statements in the patents, the district court had interpreted the claims to require a KARI defined with respect to the NADPH cofactor only.
The crux of the Federal’s Circuit’s decision was its holding that the district court erred in its claim construction, specifically concluding that the lower court got it wrong when it interpreted the claim term “acetohydroxy acid isomeroreductase”, i.e., KARI, to mean an enzyme that is solely NADPH dependent.
The Federal Circuit found that the plain meaning of the term KARI does not in itself impose any limitation on the cofactor or the source of electrons needed for the reaction.
In addition, the appeals court found that nothing in the patents limited the definition of KARI to being only NADPH dependent:
The patent’s definition at least excludes as-yet-undiscovered KARI enzymes that could catalyze conversion of AL to DHIV without using NADPH at all. Moreover, the description of specific types of KARI as NADPH-dependent does not clearly express an intent to redefine all KARI “using NADPH” as KARI that must be NADPH-dependent.
Ultimately, the Federal Circuit made its own determination on claim construction, defining “acetohydroxy acid isomeroreductase” by its enzyme classification number and catalytic activity:
[T]he term “acetohydroxy acid reductisomerase” is construed as “an enzyme, whether naturally occurring or otherwise, known by the EC number 126.96.36.199 that catalyzes the conversion of acetolactate to 2,3-dihydroxyisovalerate.”
Therefore, the appeals court vacated the denial of Butamax’s motion for summary judgment of infringement because the lower court now has to consider the question of whether Gevo’s enzymes infringe the patents-in-suit under the broader claim construction.
Interestingly, this case previously went up to the Federal Circuit on appeal of a preliminary injunction decision, and the appeals court at the time warned the district court to reconsider its claim construction of the disputed term.
As to validity of the Butamax patents, the Federal Circuit reviewed the record and found sufficient evidence – in the form of expert testimony and scientific publications – to create a genuine issue of fact that the ’889 Patent meets the written description requirement because those of skill in the art know how to deactivate the genes that express the claimed pathway.
So the case will go back down to the district court for another round on infringement and validity.