RADIOIMMUNOASSAY FOR COPPER CONTAINING SUPEROXIDE-DISMUTASE

Highly radioactive rat and bovine copper containing superoxide dismutases (Cu-SOD) up to 1700 Ci/mmole of protein were prepared by iodination with 125I and chloramine T. Labelled human Cu-SOD was obtained by coupling the enzyme with N-succinimidyl 3-(4-hydroxy, 5-(125I)-iodophenyl) propionate. These tracer molecules can be used with anti-bovine or anti-human Cu-SOD antisera to estimate various Cu-SODs as protein (rat, bovine, human) with a sensitivity of 20-80 picogrammes, using standard radio-immunochemical techniques. Control in vivo of the steady state concentration of the radical ion superoxide O2• strongly depends upon the quantity of superoxide dismutase (SOD) present (1). There are several types of enzyme, which are ubiquitous among all aerobic species, but differ in their subcellular location and in the nature of the metal at the active site (2). It is thus of interest to develop a sensitive, specific, and easy assay of the enzymes, particularly if discrimination between mangano and cuprozinc SODs can be achieved. Radioimmunological techniques answer these requirements and can contribute to the solution of a wide variety of problems connected with the metabolism of molecular oxygen. © 1979.