Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving transferase
Patent
1993-09-13
1995-07-04
Beisner, William H.
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving transferase
435 4, 435 26, 435188, 435194, 435232, C12Q 148, C12Q 132, C12N 910, C12N 988
Patent
active
054299306
ABSTRACT:
An improved kinetic assay is provided for spectrophotometrically determining the dissolved carbon dioxide (CO.sub.2) content of a body fluid (e.g., blood, plasma or serum), wherein at about pH 8.0 the CO.sub.2 is present substantially as bicarbonate ion (HCO.sub.3.sup.-). The assay sample is first subjected to a coupled reaction mixture containing phosphoenolpyruvate (PEP) and phosphoenolpyruvate carboxylase (PEPC) which enzymatically catalyzes conversion of HCO.sub.3.sup.- to oxaloacetate (OA). The OA produced is subjected to a second coupled reaction mixture containing nicotinamide adenine dinucleotide (NADH) and malate dehydrogenase (MDH) which thereby reduces the OA to malate and oxidizes the NADH to NAD.sup.+. The CO.sub.2 level in the body fluid sample may indirectly be determined by spectrophotometrically measuring the change in NADH concentration. According to the invention, an amount of an inhibitor is added to the reaction mixture which renders the reaction kinetics of the system essentially first order over the entire bicarbonate concentration range of interest. A useful inhibitor substantially satisfies a model represented by the monoexponential equation
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Cunningham Bryce A.
Johnson George F.
Punzalan Rubio R.
Beisner William H.
Bio-Research Products, Inc.
Degen Nancy J.
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