Appeal No. 1996-4119
Application No. 08/261,406
inhibitor in solution, and thereafter precipitating the alpha-1-proteinase inhibitor by
the addition of more ZnCl2.” Appellants then argue (Brief, page 9) that the examiner
does not point to prior art suggesting such a selective precipitation.
Bollen discloses (column 2, lines 48-52) “[a] crude bacterial or yeast extract
is preferably partially purified such as by selective ammonium sulfate precipitation
followed by … selective precipitation of contaminating proteins such as by use of a
polyalkyleneglycol.” Reversing the order of process steps is prima facie obvious in
the absence of new or unexpected results. In re Burhans, 154 F.2d 690, 692, 69
USPQ 330, 332 (CCPA 1946). We find no evidence of record demonstrating that
the claimed process produces an unexpectedly different result than that of the prior
art process. Therefore, it would have been prima facie obvious to reverse the steps
disclosed in Bollen to first use a polyalkyleneglycol (e.g. PEG), followed by
precipitation with a salt (ammonium sulfate).
The examiner applies Ng (Answer, page 4) to teach the use of zinc chloride
precipitation to purify proteins. Where, as here, the prior art recognizes two
components to be equivalent, an express suggestion to substitute one for another
need not be present in order to render such substitution obvious. In re Fout, 675
F.2d, 301, 213 USPQ 532, 536 (CCPA 1982). Therefore, in our opinion, it would
have been prima facie obvious to substitute ZnCl2, for the ammonium sulfate taught
by Bollen.
The examiner provides Harris to teach that salts (page 154) and PEG (page
160) are routinely used for precipitating proteins. Harris teach (page 160) with
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