Appeal No. 1996-4119
Application No. 08/261,406
Claim 1:
The examiner states (Answer, bridging paragraph, pages 5-6):
It would have been obvious to one with ordinary skill in the art at the
time [a]ppellants’ invention was made to determine all operable and
optimal parameters the purification of alpha-1-antitrypsin by Bollens’
procedure as modified by Ng and Harris, such as the volume the
impure protein is suspended in, in what the protein is suspended, and
the concentration of the PEG/ZnCl2 precipitant because it is desirable
to choose buffer conditions and to have the components of a
precipitation present in ratios that insure the highest yield and purity of
the protein that is being purified. Further, it would have been obvious
to one with ordinary skill in the art at the time [a]ppellants’ invention
was made to insert an additional anion-exchange chromatography
step after the first anion-exchange step in the purification process of
alpha-1-antitrypsin by the protocol of Bollen as modified by Ng and
Harris, because it is desirable in the art to purify a therapeutic product
to the greatest extent possible in order to produce a product having
few impurities, and having homogeneous properties, and additional
purification steps would accomplish this.
As noted by the examiner (Answer, page 4) Bollen discloses all the process
steps of appellants’ claim 1, except the use of ZnCl2 in the PEG precipitation step
and a separate ZnCl2 precipitation step. Bollen discloses (column 4, lines 3-21) the
use of a Tris-HCl buffer and a phosphate buffer, both of which comprise water.
Therefore, Bollen does disclose “suspending the impure protein fraction comprising
I1-proteinase inhibitor in water,” as recited in appellants’ claim 1. Bollen also
discloses the use of ammonium sulfate precipitation (column 2, line 42, to column 3,
line 4).
Appellants state (Brief, page 8) that “claim 1 requires the precipitation of
unwanted proteins by the addition of PEG and ZnCl2, leaving alpha-1-proteinase
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