[Estimation of serine- and threonine dehydratase activity of blood serum]

A procedure for estimation of serine dehydratase (SDH) and threonine dehydratase (TDH) activities in blood serum was based on the colorimetric measurement of the products, increasing after deamination of 1-serine (pyruvic acid) and 1-threonine (alpha-ketobutyric acid) using the reaction with 2,4-dinitrophenyl hydrazine in an alkaline medium. Conditions for the enzymatic reaction were developed. Activity of enzymes was expressed as micrometer of the reaction products per 1 L of blood serum within 1 hr of incubation at 37 degrees. Blood serum from normal donors did not exhibit the SDH and TDH activities. The enzymatic activity was estimated in 126 patients with various impairments of liver tissue. The procedure developed was shown to be highly sensitive and informative. It enabled to detect both the earliest periods of the cytolytic syndrome and transition of the syndrome into its irreversible step.