Appeal No. 1996-4119
Application No. 08/261,406
achieve a purification process which is effective and efficient.” However, Bollen
also discloses (column 3, lines 49-54) that the “AAT resulting from this procedure
can, if desired, be subjected to further purification steps to remove trace
contaminants such as by affinity chromatography.” Therefore, we are not
persuaded by appellants’ reference to Bollen (column 2, lines 7-12).
In our opinion, the examiner met her burden of establishing a prima facie
case of obviousness.
Claim 5:
Appellants argue (Brief, page 11) that “[t]here is certainly nothing in Figure 1
of Ng, or any other part of that article suggesting the use of 0.25 to 0.75 mM ZnCl2 in
combination with PEG to selectively precipitate impurity proteins, but not I1-
proteinase inhibitor.”
The examiner applies Ng to teach that ZnCl2, can be used to precipitate
proteins. As discussed supra, in our opinion, it would have been prima facie
obvious to use ZnCl2, to maintain the ionic strength of the solution, since ZnCl2, and
a metal chelate column (which can be a Zn++ chelate column) are used in
subsequent purification steps.
Harris teaches (page 159) the ionic strength of the solution should be
between 0.05-0.2. With regard to the difference between the ionic strength taught
by Harris and the “concentration of 0.25 to 0.75” limitation of apellants’ claim 5, we
note that the discovery of an optimum value of a result effective variable is ordinarily
within the skill of the art. In re Boesch, 617 F.2d 272, 276, 205 USPQ 215, 219
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