A New Look at the Measurement and Interpretation of Enzyme Assays

Some methodological problems in clinical enzymology, including instability of enzymes in the incubation mixture and requirements for optimal reaction conditions, are highlighted. The importance of a knowledge of fundamental enzyme biochemistry and physiology as the basis for their diagnostic application is stressed, and the different behaviour of some hepatic enzymes—namely, GOT, GPT, γ-GT, and OCT, in various pathological conditions is traced back to their characteristic biochemical and physiological properties. In the field of urinary enzymes a knowledge of the ideal requirements for the enzyme investigation of the various renal functions and of the properties of potentially valuable enzymes permits a critical selection of the really useful ones.