Appeal No. 1996-0223
Application No. 07/931,563
According to the examiner, it would have been obvious to immobilize the calcium-dependent
antibodies of Swanson in order to purify (-carboxyglutamyl modified prothrombin which is an active
protein, while prothrombin without (-carboxyglutamyl residues is inactive, (answer, page 5) because
“[t]he teachings of Swanson et al. on the characterization of calcium-dependent antibodies and the
release of prothrombin from these antibodies by EDTA and the teachings of Falb et al. on the use of
immobilized antibodies to purify protein antigens provide the requisite motivation and expectation of
success for purifying prothrombin by the use of calcium-dependent antibodies” (answer, page 11).
Appellants do not dispute that using immobilized antibodies to purify antigens is old in the art
(brief, page 11). The argument is that “normal human plasma contains only fully carboxylated, fully
active protein, and non-conformation specific antibodies can be used to isolate the active form of
prothrombin” (brief, page 13, footnote omitted). In other words, the examiner
has not explained why the skilled artisan would have chosen Swanson’s calcium-dependent antibody as
the immobilized antibody for the purification of prothrombin, as opposed to either a non-conformation
specific antibody or a calcium-independent antibody of Swanson (N.B. Figure 2A clearly shows that
Swanson’s calcium-dependent antibody binds plasma prothrombin).
The examiner opines that EDTA would be of no use in releasing prothrombin from a calcium-
independent antibody (answer, page 10) and that the “harsh treatments reported by Swanson et al. in
their in vitro experiments would not be of value in purifying bioactive prothrombin” (answer, page 11).
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