Appeal No. 1997-3501
Application No. 08/253,232
contaminants, and Mitra’s and Wang’s stabilizers will prevent denaturation of
a protein during heat treatment procedures. It would have been obvious to
one with ordinary skill in the art at the time Applicants’ invention was made to
determine all operable and optimal parameters of a protein purification
procedure such as the buffer components and concentrations for all steps,
and the type and concentration of precipitating agents and the types of
purification steps as shown by Harris, because it is desirable to have a
procedure that will enable the protein to be purified to the greatest extent
with as few as contaminants as possible, and it is routine in the art to do so.
Austen describes the chromatographic separation of Factor VIII complexed with
ristocetin, i.e., von Willebrand factor, on aminohexyl sepharose. After binding of the
complex which includes the vWF, to aminohexyl sepharose, the ionic strength is gradually
increased with sodium chloride, successively releasing ristocetin from Factor VIII, to allow
purification of Factor VIII. Austen, page 672. The examiner acknowledges that Austen
does not disclose components of the claimed chromatography buffers, does not teach
precipitation steps in a process for the isolation of vWF, and does not teach pasteurization
of vWF, or the conditions for pasteurization. Examiner’s Answer,
page 4.
The examiner relies upon Mathews for the disclosure that blood proteins, such as
Factor VIII:C, may be purified by anion exchange chromatography in the presence of a
sugar, sugar alcohol, amino acids and salt thereof, as well as the use of calcium chloride
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