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Clinical Chemistry, Vol 20, 43-50, Copyright © 1974 by the American Association for Clinical Chemistry
1 Pediatric Microchemistry Laboratory, University of Colorado
Medical Center, Denver, Colo. 80220.
We examined the measurement of serum aspartate and alanine aminotransferase activities with a short-interval enzyme-activity analyzer. Double-beam spectrophotometry was used to elucidate the source of errors in such measurements. For both enzymes the principal error sources are: (a) the presence of endogenous substrate for lactate dehydrogenase, and (b) reaction of 2-oxoglutarate with serum glutamate dehydrogenase and ammonium ions added to the reaction mixture in admixture with the secondary enzymes of the coupled reactions. In the case of serum aspartate aminotransferase, a less important source of error is the reaction of serum alanine aminotransferase with endogenous substrate. Use of 2-oxoglutarate as a reaction initiator in conventional methods causes errors. Suitable blank reagent mixtures are described that permit accurate, rapid measurement of these activities by double-beam spectrophotometry in a short-interval enzyme-activity analyzer.
Accepted on October 29, 1973
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