19] Estimation of animal transaminases

Abstract

Publisher Summary This chapter discusses the estimation of animal transaminases. The methods discussed for the purpose are spectrophotometric measurement of oxalacetic acid formation and manometric estimation of glutamic acid by means of glutamic acid decarboxylase. The spectrophotometric measurement of oxalacetic acid formation method may be used with any transamination system in which one of the components, either added as substrate or formed as a reaction product, has a measurable characteristic absorption at a suitable wavelength. In principle the method requires that the other components do not have an interfering absorption at the wavelength used for a given compound which interferes. It thus is necessary to have data on the absorption properties of all the components in any given system. Although the spectrophotometric method is limited to only a few transaminating systems, its usefulness as a microprocedure and its suitability especially for kinetic studies make it the method of choice in some instances. The principle of manometric estimation of glutamic acid by means of glutamic acid decarboxylase method is that of using a specific amino acid decarboxylase and estimating CO 2 formation manometrically. The formation or disappearance of any given amino acid participating in a transamination reaction can be measured provided that a specific and reasonably active enzyme preparation is available. Since glutamic acid formation and disappearance are so commonly estimated to measure transaminase activity and since a highly specific and active enzyme preparation is available for this purpose, this chapter discusses only the use of glutamic acid decarboxylase.