Fixed-time kinetic assay of plasma ammonia, with NADPH as cofactor, with a centrifugal analyzer.

Abstract:

:We describe a fixed-time, enzymatic, reaction-rate procedure for determining plasma ammonia with a centrifugal analyzer (Rotochem IIA/36; American Instrument Co., silver Spring, MD 20910), with NADPH as cofactor. The reaction is based on that of da Fonseca-Wollheim's modification [J. Clin. Chem. Clin. Biochem. 11, 421 (1973)] of the Kirstein reaction, which depends on the catalytic amination of alpha-ketoglutarate by the action of glutamate dehydrogenase with NADPH as the cofactor instead of NADH. Use of NADPH minimizes interference from endogenous reactions such as that between lactate dehydrogenase and pyruvate. This method permits shortened preincubation time and thus improves both specificity and precision. This assay requires 100 microliter of freshly collected heparinized plasma, gives quantitative analytical recovery, and the standard curve is linear to 430 mumol/L. Data are presented comparing results with those by two other enzymatic ammonia procedures.

journal_name

Clin Chem

journal_title

Clinical chemistry

authors

Li PK,Shull BC

subject

Has Abstract

pub_date

1979-04-01 00:00:00

pages

611-3

issue

4

eissn

0009-9147

issn

1530-8561

journal_volume

25

pub_type

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