Appeal No. 2000-0630
Application No. 07/780,717
possible residues. Their stick models suggest that the polypeptide
backbone of the core streptavidin runs up and down in eight $-strands
forming a barrel structure.
Hendrickson et al. teach nothing about a 16-133 core streptavidin - there
was no such polypeptide in existence or contemplated at the time. All
Hendrickson et al. say is that their picture of their 13-139 protein was too
faint to include the terminal residues. While their models showing residues
14-136 and 16-133 of their 13-139 core show that these residues suffice to
complete the $-barrel structure, the same can be said of a 15-135 residue
model or a 17 to 132 residue model, or any of numerous other arbitrarily
truncated cores that nevertheless retain a $-barrel model structure.
Appellants argue that Sano provides no suggestion to truncate the 13-139 core, as
“such a suggestion would fly in the face of the only evidence that (1) the core did not
present an aggregation problem and (2) the core was already at a minimum size
necessary to retain activity.” Brief, page 4.
We disagree with both the examiner’s and appellants’ interpretations of the prior
art. Pähler states that the streptavidin referred to in the reference is a commercial product,
and that “the Apcel product has been processed by an undisclosed protocol to a minimal
size that still retains full activity” (page 13934, column 1, citing a personal communication).
Thus, Pähler provides no direct evidence regarding the minimal functional size of
streptavidin. Pähler also notes that this particular commercial product is highly soluble, in
contrast to previous experience, but does not suggest any reason for the high solubility
(page 13933, last paragraph). Even if one of ordinary skill would have understood Pähler
to teach a minimal active core of residues 14-138 or 13-139, Sano provides evidence that
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