Engvall’s example 1 does not explicitly identify the background absorbance or the absorbance
for a sample having a great excess of ligand.
a) B* and the background absorbance level
In performing the Scatchard analysis, Bergland assumed the background absorbance value to
be .01. At page 3 of her declaration (E128), Bergland states:
9. Referring to Exhibit E57 at page 589, I prepared my table
(Exhibit E55 ) in a similar fashion. Thus, referring to the third[53]
column of the table, which gives values for B , this represents bound*
absorbance minus background. I used a value of 0.01 for the
background, as that is the value that is generally accepted.
While Bergland thought .01 was appropriate, Dr. Langone had a different view of the
appropriate background level. Dr. Langone also estimated the affinity constant from Engvall’s
example 1 data but using another technique. ER 3511-20. Dr. Langone, however. was of the view
that .1, not .01, was the background absorbance level. Dr. Langone stated (ER 3514-15):
I have taken a conservative approach in the sense that I have
stated that the background, appropriate background for this
experiment is an absorbance value of 0.1. . . .
Q. Doctor, before you go ahead and tell us what you did to come
up with that number, let me ask you; you said you took a
conservative approach, and used, as the background value,
0.1, is that correct, that’s what you did?
A. That’s correct.
Q. Why did you do that, and what makes it conservative?
A. I did that to be conservative in the sense that the binding
affinity calculated at the 12.5 dose range would be lower than
if we chose a dose of alphafeto protein less that. If you look
at the alphafeto protein concentration on page 12 [of the
Engvall specification], given as 6.5 micrograms per ml., and
look at the corresponding absorbance, the absorbance is 0.13.
That, to me, is a value close to 0.1, and for that reason, I
chose to use a higher value of 12.5 micrograms per ml. for
these calculations.
53
The David et al. Motion to Suppress Evidence (Paper 331) , pp. 14-15) objects to this Exhibit along
with Exhibit E56 as misleading. This argument goes to the weight of the evidence, not to its admissibility. The motion
is denied as to those exhibits.
26
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