Variation in apparent enzyme activity in two-enzyme assay systems: phosphoenolpyruvate carboxylase and malate dehydrogenase.
We have employed the two-enzyme assay system for phosphoenolpyruvate to investigate the effect on the apparent phosphoenolpyruvate carboxylase (PEP-C) activity of the use of malate dehyrogenase (MDH) that has been stabilized in either glycerol or (NH4)2SO4. The type of MDH stabilizer has a marked effect on the apparent activity of the PEP-C. The apparent activities of the PEP-C are 1.34 and 0.43 U/mg in the presence of glycerol and salt-stabilized MDH, respectively. The implications of the observations for diagnostic assays are discussed.
Pafra LTD, Biopreservation Division, Cambridge, United Kingdom.
R H
RH
Hatley
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F
Franks
D002262:Carboxy-Lyases / Q000378:metabolism*; D008291:Malate Dehydrogenase / Q000378:metabolism*; D010728:Phosphoenolpyruvate / Q000032:analysis*; D010730:Phosphoenolpyruvate Carboxylase / Q000378:metabolism*
D010728:Phosphoenolpyruvate; D008291:Malate Dehydrogenase; D002262:Carboxy-Lyases; D010730:Phosphoenolpyruvate Carboxylase