Appeal No. 1997-0838
Application 08/235,238
Selmeci teaches that “susceptibility of LDH isozymes to proteolysis varies,” and
mentions subtilisin as an example of a peptidase that digests LDH , but leaves LDH5 1
unaltered. Because conformational changes induced by coenzymes and substrates also
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affect susceptibility of isozymes to proteolysis, Selmeci investigates the effect of NAD and
NADH on the proteolysis of LDH and LDH by trypsin. Trypsin alone rapidly denatures1 5
LDH , and to a lesser extent, LDH ; NADH has virtually no effect on proteolysis by trypsin,1 5
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but NAD has an initial protective effect on LDH .
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Sanford briefly discusses several methods of selectively inhibiting LDH isozymes,
among them, denaturation with urea or oxalate, and concludes that “[t]he physical-chemical
procedures suffer from lack of sufficient specificity.”
The examiner believes that:
It would have been obvious to one of ordinary skill in the art at the time the
invention was made to selectively determine LDH isoenzyme activity by
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combining the differential inhibitors of IATRON/SANFORD (protein
denaturing agents) and SELMECI (protease) because their expected
combined effect would be to more effectively eliminating [sic] the enzymatic
activity of LDH -LDH isoenzymes. Such a combination of inhibitors would
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have been further motivated by SANFORD’S disclosure that agents such as
urea alone suffer from lack of sufficient specificity - - i.e. they do not
adequately distinguish between heart isoenzymes, LDH and LDH - - and1 2
SELMECI’s disclosure that LDH -LDH show a variable susceptibility to
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protease inhibition, while LDH activity is unaffected.
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(Examiner’s Answer, pages 7 and 8)
Appellants argue that the combined references not only fail to suggest the general
concept of combining a protease with a denaturing agent to inhibit LDH , LDH , LDH , and2 3 4
LDH (for a number of reasons set forth on pages 10 through 16 of the Brief), but most
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