Appeal No. 1999-1730
Application No. 08/478,205
of the difference in color between the naturally occurring luciferase variants.
Therefore, the examiner reasoned that
one of ordinary skill in the art would reasonably expect that these
positions must be important for defining the environment
surrounding the luciferin substrate and therefore the color of the
emitted light. One of ordinary skill in the art would reasonably
expect that the introduction of other amino acids into these
positions would produce mutant enzymes with additional colors of
emitted light as each amino acid has different chemical properties
(i.e., charge, polarity, hydrophobicity etc.) and therefore would alter
the environment around the luciferin substrate in different ways.
Id., page 8.
The examiner also concluded that it would have been “obvious to mutate
other amino acids within the region of amino acids 223-247.” Id. She found
motivation to do so based on the following passage in the Wood dissertation:
The three substitutions that cause most of the color shift between
yellow green and orange are located in a 25-amino acid segment of
the sequences, from positions 223-247. The probability of this
occurring by chance is about 0.01. . . . [I]t is likely that this region
contains many, if not most, of the potentially suitable amino acids
that affect the color of luminescence. It is expected that such a
region would be close to the binding site of luciferin.
Wood dissertation, page 221.
Appellants argue that the cited references would not have rendered the
claimed DNAs obvious to those of ordinary skill in the art. Appellants argue that
the cited references would not have made it obvious to alter amino acid positions
other than the three positions taught by the references to be important to light
color, nor would they have made it obvious to make substitutions other than the
naturally occurring variations at those three positions.
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