Appeal No. 1997-0838 Application 08/235,238 Humans produce five lactate dehydrogenase (LDH) isozymes, LDH , LDH , LDH ,1 2 3 LDH , and LDH , which catalyze the same reaction, but differ in certain of their physical4 5 and/or chemical properties. Each isozyme is composed of four subunits which may be heart muscle type (H), or skeletal muscle type (M), or both. For example, LDH is 1 composed of four H subunits, LDH , LDH and LDH are composed of various2 3 4 combinations of the H and M subunits, while LDH is composed of four M subunits. 5 According to appellant, Each of organs has its own composition of the isozymes. For example, LDH is present in a myocardium in the largest amount. Since LDH1 1 escapes from the myocardium into blood under a condition of a myocardial infarction, a rise in serum LDH level can be diagnostic for such a disease. 1 (Specification, page 1). In its broadest aspect, the invention is directed to selective determination of LDH in 1 human serum or plasma (using an assay for total LDH activity), wherein LDH , LDH , LDH2 3 4 and LDH , also present in the samples, are inhibited with a combination of "-chymotrypsin 5 and a protein denaturing agent. Obviousness Claims 1, 4 through 6, 10, 11, 13, 15 and 16 stand rejected as unpatentable over Iatron, Selmeci and Sanford. Iatron selectively measures residual LDH activity in human serum using a protein 1 denaturing agent (urea, thiourea, guanidine, etc.) in an alkaline buffer (pH 10-11) to inactivate LDH , LDH , LDH , and LDH .2 3 4 5 3Page: Previous 1 2 3 4 5 6 7 8 9 10 NextLast modified: November 3, 2007