Appeal No. 2000-0630
Application No. 07/780,717
DISCUSSION
Claim 68, drawn to “[a] functional streptavidin consisting of residues 16 to 133
(SEQ ID NO:7) of mature streptavidin,” is representative of the claimed invention.
According to the examiner (paper no. 42, page 3):
[Hendrickson] disclose[s] that streptavidin (SA) is a tetramer and each
protomer is a simple J-barrel structure (page 2190, Abstract). [Hendrickson]
also disclose[s] that residues 16-133 of SA are sufficient to complete the J-
barrel structure (page 2194, column 1, full paragraph 1).
[Sano] teach[es] the recombinant expression of a cloned streptavidin gene in
E. Coli. [Sano] suggest[s] truncating SA at both the N- and C-termini in order
to solve any aggregation problems (page 146, paragraph bridging columns
1-2). It would have been obvious to one of ordinary skill in the art . . . to
recombinantly produce SA having residues 16-133, using the guidance of
Hendrickson and [Sano], with a reasonable expectation of success.
Appellants disagree with the examiner’s interpretation of Hendrickson. Appellants
cite Pähler, published in 1987, as background to Henderson. According to appellants,
Pähler describes crystallographic analysis of streptavidin “processed to a minimal sized
core streptavidin . . . that still retains full biotin-binding activity,” wherein it was determined
that “this minimum size core streptavidin was in fact a mixture of four cleavage products
representing residues 14-138, 13-138, 14-139 and 13-139.” Brief, page 3.
Further according to appellants (Brief, page 3):
Hendrickson et al. . . . describe further crystallographic studies of the same
core streptavidin. In tracing the alpha carbons of their image, the
investigators report that the density of the terminal residues was too weak to
include in their drawings; hence, their backbone stick models of their core
streptavidin included only residues 14-136 and 16-133 of the 13-139
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