Background. In January 2011, Butamax file suit against Gevo alleging infringement of US Patent No. 7,851,188 (the ‘188 patent). This patent discloses and claims “a recombinant microorganism having an engineered isobutanol biosynthetic pathway” that “may be used for the commercial production of isobutanol.” In August, Butamax amended its complaint to include infringement of Patent No. 7,993,889 (“the ‘889 patent”). The ‘899 patent was filed as a divisional application from the ‘188 patent and also claims a method for isobutanol production using recombinant microorganisms—i.e., yeast or other comparable microorganisms—with an engineered biosynthetic pathway.

In September 2011, Butamax filed the motion for a preliminary injection, seeking to enjoin Gevo from infringing the ‘899 patent.

The ‘899 patent. Yeast naturally produce low levels of isobutanol from the catabolism of the amino acid L-valine as a by-product of fermentation. In its patent, Butamax claimed a more cost-efficient method of producing isobutanol directly from pyruvate, a product of sugar digestion, instead of L-valine via a multi-step biosynthetic pathway:

1. Pyruvate to acetolactate, with the conversion performed by an acetolactate enzyme;

2. acetolactate to 2,3-dihydroxyisovalerate, performed by an acetohydroxy acid isomeroreductase enzyme;

3. 2,3-dihydroxyisovalerate to α-ketoisovalerate, performed by an acetohydroxy acid dehydralase enzyme;

4. α-ketoisovalerate to isobutyraldehyde, performed by a decarboxylase enzyme; and

5. isobutyraldehyde to isobutanol, performed by an alcohol dehydrogenase enzyme.

Court’s decision. In her opinion, Judge Robinson noted that the parties are essentially disputing the meaning of the term “acetohydroxy acid isomeroreductase enzyme” (known as KARI), the enzyme utilized in step b above. Specifically at issue is whether a KARI is defined with respect to NADPH or NADH cofactors, i.e., the electron donors that enable it to catalyze a reaction.

The patent, noted the judge, explicitly defines acetohydroxy acid isomeroreductase as “an enzyme that catalyzes the conversion of acetolactate to 2,3-dihydroxyisovalerate using NADPH (reduced nicotinamide adenine dinucleotide phosphate) as an electron donor.” Butamax argued that despite this definition, the term should be given its “plain and ordinary” meaning, which would be an enzyme that utilizes NADPH and/or NADH as a cofactor. Gevo, on the other hand, argues that Butamax has clearly defined the KARI by reference to its cofactor and this reference prevents a finding of infringement. “In other words, because the KARl is explicitly defined as being exclusively NADPH-dependent and defendant utilizes a primarily NADH-dependent enzyme, no infringement exists.”

The court interprets the term acetohydroxy acid isomeroreductase in the manner in which plaintiff defined it, namely, as an enzyme that is solely NADPH-dependent (as opposed to NADH-dependent or NADH and NADPH-dependent). This interpretation is supported by an examination of the specification. In particular, the court notes that other enzymes in the patent are specifically identified as using “NADH and/or NADPH as an electron donor.”

This confirms that plaintiff, who was aware of NADH-dependent KARIs, intended to limit the term acetohydroxy acid isomeroreductase to an exclusively NADPH-dependent enzyme. As the Federal Circuit explained in Abbott Laboratories v. Sandoz, Inc...when a patentee knows of the existence of two specific compounds (or in this case two specific cofactors) and nevertheless defines a term without reference to one, the failure to reference that compound evidences a clear intent to limit the term, i.e., to exclude it from the claim scope. In short, because plaintiff knew of the existence of NADH-dependency and knew how to define a term by reference to an NADH cofactor, the term acetohydroxy acid isomeroreductase is properly construed as excluding an enzyme that is in any way NADH-dependent.

...In light of the court’s construction, and the fact that defendant uses an NADH-dependent enzyme to catalyze its step two reaction, the court finds it unlikely that plaintiff will prevail on its claim of infringement.

—Judge Robinson

Commenting on the decision, Brett Lund, EVP and General Counsel for Gevo also said that Gevo has consistently maintained that it does not infringe Butamax’s patents, because the Gevo-created NKR enzyme used in its engineered yeast strains uses NADH, and not NADPH, as an electron donor. Lund added that NADH enables Gevo’s yeast strains to produce isobutanol at much greater efficiencies than strains using NADPH.

Separately, the US Patent and Trademark Office (USPTO) has rejected the Butamax claims that Gevo challenged, Lund noted, finding those claims as unpatentable in view of a collection of prior art as indicated in reexamination case files (Serial No. 95/001,735 for the ‘889 Patent and Serial No. 95/001,857 for the ‘188 Patent).

In response to the decision, Butamax maintained that it has strong grounds for making its request for a preliminary injunction and said it plans an immediate appeal.

The court’s decision is not a final determination of infringement or invalidity concerning the 188 and 889 patents as it is merely a determination that the extraordinary remedy of a preliminary injunction is not available at this time. This is an early step in a long and complex litigation process.

—Paul Beckwith, Butamax CEO

Butamax said that its request for the preliminary injunction was only based on a select number of claims of Butamax’s ‘889 patent. At trial, Butamax’s case on all the claims of both the ‘188 and ‘889 patents will be heard. Full trial in this case is scheduled for April, 2013. Additionally, Butamax said that it has several other patents and patent applications it will seek to enforce as appropriate.