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    • 3. 发明授权
    • Kinetic enzyme assay for determining the CO.sub.2 content of body fluids
using PEP carboxylase with inhibitor
    • 动力学酶法测定使用PEP羧化酶与抑制剂的体液二氧化碳含量
    • US5480777A
    • 1996-01-02
    • US375946
    • 1995-01-20
    • Bryce A. CunninghamGeorge F. JohnsonRubio R. Punzalan
    • Bryce A. CunninghamGeorge F. JohnsonRubio R. Punzalan
    • C12Q1/32C12Q1/48C12Q1/527C12N9/10C12N9/88
    • C12Q1/48C12Q1/32C12Q1/527
    • 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 phospho-enolpyruvate 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 AND.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 equationA.sub.t =(A.sub.o -A.sub..infin.)e.sup.-kt +A.sub..infin. [I]A sufficient quantity of the inhibitor is present to substantially cause the coupled reactions to follow the model equation [I] and yield a number which is within about .+-.200% of the noise level of the spectrophotometer used for the assay when each absorbance value is applied to the equation ##EQU1## Best results have been obtained through use of an inhibitor which provides an anion selected from the group consisting of ClO.sub.3.sup.-, ClO.sub.4.sup.-, SCN.sup.-, or I.sup.-.
    • 提供改进的动力学测定用于分光光度测定体液(例如血液,血浆或血清)的溶解二氧化碳(CO 2)含量,其中在约pH8.0时,CO 2基本上以碳酸氢根离子(HCO 3 - )存在。 首先对测定样品进行含有磷酸烯醇丙酮酸(PEP)和磷酸烯醇丙酮酸羧化酶(PEPC)的偶联反应混合物,其中酶促催化HCO3-转化为草酰乙酸(OA)。 生成的OA经受含有烟酰胺腺嘌呤二核苷酸(NADH)和苹果酸脱氢酶(MDH)的第二偶联反应混合物,从而将OA还原为苹果酸,并将NADH氧化成为+。 通过分光光度法测量体液样品中的二氧化碳水平可以间接测定NADH浓度的变化。 根据本发明,将一定量的抑制剂加入到反应混合物中,使得系统的反应动力学在感兴趣的整个碳酸氢盐浓度范围内基本上是一级。 有用的抑制剂基本上满足由单指数方程表示的模型At =(Ao-A INFINITY)e-kt + A INFINITY [I]存在足够量的抑制剂以基本上使偶联反应遵循模型方程[I ],并且当将每个吸光度值应用于方程式时,产生的数值在用于分析的分光光度计的噪声水平的约+/- 200%之内。[II]通过使用抑制剂获得最佳结果 其提供选自ClO 3 - ,ClO 4 - ,SCN-或I-的阴离子。
    • 4. 发明授权
    • Kinetic enzyme assay for determining the CO.sub.2 content of body fluids
using PEP carboxylase with inhibitor
    • 动力学酶法测定使用PEP羧化酶与抑制剂的体液二氧化碳含量
    • US5429930A
    • 1995-07-04
    • US119586
    • 1993-09-13
    • Bryce A. CunninghamGeorge F. JohnsonRubio R. Punzalan
    • Bryce A. CunninghamGeorge F. JohnsonRubio R. Punzalan
    • C12Q1/32C12Q1/48C12Q1/527C12N9/10C12N9/88
    • C12Q1/48C12Q1/32C12Q1/527
    • 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 equationA.sub.t =(A.sub.o -A.sub..infin.)e.sup.-kt +A.sub..infin. [I]A sufficient quantity of the inhibitor is present to substantially cause the coupled reactions to follow the model equation [I] and yield a number which is within about .+-.200% of the noise level of the spectrophotometer used for the assay when each absorbance value is applied to the equation ##EQU1## Best results have been obtained through use of an inhibitor which provides an anion selected from the group consisting of ClO.sub.3.sup.-, ClO.sub.4.sup.-, SCN.sup.-, or I.sup.-.
    • 提供改进的动力学测定用于分光光度测定体液(例如血液,血浆或血清)的溶解二氧化碳(CO 2)含量,其中在约pH8.0时,CO 2基本上以碳酸氢根离子(HCO 3 - )存在。 首先对测定样品进行含有磷酸烯醇丙酮酸(PEP)和磷酸烯醇丙酮酸羧化酶(PEPC)的偶联反应混合物,其中酶促催化HCO3-转化为草酰乙酸(OA)。 生成的OA经受含有烟酰胺腺嘌呤二核苷酸(NADH)和苹果酸脱氢酶(MDH)的第二偶联反应混合物,由此将OA还原为苹果酸,并将NADH氧化成NAD +。 通过分光光度法测量体液样品中的二氧化碳水平可以间接测定NADH浓度的变化。 根据本发明,将一定量的抑制剂加入到反应混合物中,使得系统的反应动力学在感兴趣的整个碳酸氢盐浓度范围内基本上是一级。 有用的抑制剂基本上满足由单指数方程表示的模型At =(Ao-A INFINITY)e-kt + A INFINITY [I]存在足够量的抑制剂以基本上使偶联反应遵循模型方程[I ],并且当将每个吸光度值应用于方程式时,产生的数值在用于分析的分光光度计的噪声水平的约+/- 200%之内。[II]通过使用抑制剂获得最佳结果 其提供选自ClO 3 - ,ClO 4 - ,SCN-或I-的阴离子。