DETERMINATION OF THE KINETIC-PARAMETERS OF ADENOSINE-DEAMINASE BY ELECTROPHORETICALLY MEDIATED MICROANALYSIS

The possibility of determining the Michaelis constant of the irreversi ble deamination of adenosine to inosine by adenosine deaminase, using capillary electrophoresis, was investigated. This paper describes the use of electrophoretically mediated microanalysis (EMMA) as the techni que for carrying out the assay. Initial reaction velocities of the enz ymatic reaction were estimated from the peak area of inosine, and the Michaelis constant was calculated according to the Lineweaver-Burk equ ation. The result (K-m = 5.3 x 10(-5) M +/- 8 x 10(-6) M) was consiste nt with previously reported values. Using the present method, a total amount of as few as 1.2 fmole of enzyme and 9.2 ng of substrate were i njected in the capillary for the construction of a Michaelis Menten cu rve (seven concentrations of substrate, each concentration analyzed in triplicate), which is far smaller than the quantities required in con ventional methods.