Interference No. 102,572
used to calculate % yield. Wetzel, ¶ 9 (CR-25).
(24) Perry testified that she performed a refolding experiment on the cotransformed
cell paste received from Mumford. The paste was sonicated and centrifuged to isolate the
refractile bodies. Perry analyzed the refractile body preparations by SDS-PAGE. The
sample was resuspended in urea, dialyzed, and then assayed. Later Perry analyzed
another reconstitution experiment from denaturant solubilized refractile body preparations
of cotransformed cells. Perry found that the heavy and light chains were insoluble, and that
dialysis into urea was necessary to obtain activity. She stated “[T]he reconstitution of
cotransformed cell extracts utilizing the optimal conditions for the reconstitution of
hybridoma cell produced antibody chains was significantly higher than the background”.
Perry, ¶ 13 (CR26-27).
(25) Wetzel testified that he and Perry , between March 18, and March 24, 1983,
performed an experiment in which CEA-binding activity was generated after refolding. He
testified that the results showed a refolding yield of 0.76% starting from a cotransformed
cellular extract and a yield of 0.32% starting from a mixture of a heavy chain S-sulfonate
and the urea-solubilize crude extract of light chain producing cells. The value of 1580 ng/ml
in the cotransformed refolding reaction was significantly higher than the background levels
of apparent activity obtained from controls of either heavy chain alone (441ng/ml) or light
chain alone (108ng/ml); these latter values are said to arise from the non-specific binding
to CEA in the assay. Wetzel concluded that this data shows “that heavy and light chain
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