Appeal No. 1996-4119
Application No. 08/261,406
reference to PEG that “[t]he mechanism of precipitation is similar to that of
precipitating by organic solvents.” In re Mills, 470 F.2d 649, 651, 176 USPQ 196,
198 (CCPA 1972)(“[a]ll the disclosures in a reference must be evaluated”). Harris
teaches (pages 157-160) precipitation by organic solvents. Harris teaches (page
159) with respect to organic solvents that “[t]he ionic strength of the solution should
be between 0.05-0.2.” As the mechanism of PEG precipitation is similar to that of
organic solvent precipitation, one would expect ionic strength to be relevant in PEG
precipitation as well. In this regard, we note that appellants’ claim 1 “suspends the
impure protein fraction comprising I1-proteinase inhibitor in water.” While Bollen
does not make an express statement regarding the addition of salt to the PEG
precipitation, we note that Bollen discloses (column 4, lines 3-21) using a Tris-HCl,
or phosphate buffer for the PEG precipitation, thus maintaining the appropriate ionic
strength for the precipitation. In our opinion, it would have been prima facie obvious
to use ZnCl2, to maintain the ionic strength, since ZnCl2, and a metal chelate column
(which can be a Zn++ chelate column) are used in subsequent purification steps.
Therefore, we are not persuaded by appellants’ argument (Brief, page 11)
that “[h]ere, there is simply no suggestion in the prior art as a whole to combine the
various specific process steps, even if individually they were known to achieve
applicants’ process.” Appellants’ rely (Brief, page 10) on the disclosure in Bollen
(column 2, lines 7-12) that “… While the individual steps are, in a general sense,
standard protein purification techniques, particular steps in a particular sequence
must be selected from the myriad possibilities of process steps and sequences to
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