The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 04, 1995
Filed:
Sep. 13, 1993
Bryce A Cunningham, Coralville, IA (US);
George F Johnson, Iowa City, IA (US);
Rubio R Punzalan, Iowa City, IA (US);
Bio-Research Products, Inc., Coralville, IA (US);
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