Appeal No. 2005-1383
Application No. 09/364,847
constructions are well known and widely used in the art, it would have been obvious to
one of ordinary skill in the art to construct a protein fusion comprising two catalytically
active enzymes which act on substrate in successive reactions in a PHA biosynthetic
pathway. Although, as discussed in footnote 4, above, we find that the protein fusion of
representative claim 1 does not require the presence of a peptide linker (when Ln is
zero), we point out that given the teachings of Bülow that the use of short linkers two to
ten amino acids in length produces optimal results in bifunctional enzymes, it would
have been further obvious to said persons to include a linker peptide in said fusion.
We disagree with the appellants that the teachings of Bülow do not provide a
reasonable expectation of success. As discussed above, Bülow discloses that (i) as
long as “the entire primary sequences of the native enzymes are maintained in the
fusion enzymes, the enzymes usually retain most of their native specific activities
despite being fused together” (p. 230, col. 1, para. 1); and (ii) “[o]ver the past few years
a variety of artificial bifunctional enzymes have been prepared by gene fusion in vitro”
(p. 227, col. 2, last para.). In our view, these teachings demonstrate that the technique
of combining enzymes which act on substrate in successive reactions is widely
applicable. Moreover, we point out that representative claim 1 is not directed to a
protein fusion consisting of specific catalytically active enzymes but, rather, it is directed
to classes of enzymes involved in a PHA biosynthetic pathway. Accordingly, given the
breadth of the claim, it is not clear that appellants’ argument addresses a particular
limitation present therein. Nevertheless, we find that those skilled in the art would have
reasonably expected the technique taught by Bülow to be equally successful using the
claimed classes of enzymes recited in claim 1. Obviousness does not require absolute
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