A simplified assay method of superoxide dismutase activity for clinical use.

A simple and inexpensive assay method of superoxide dismutase (SOD) activity of various biological materials has been developed. SOD activity can easily be measured by reading the medium's intense absorbance directly, and many samples can be treated in a short time using a reaction stopper which acts for a long time. Reproducibility of the assay method was excellent for the sample from an individual estimated at two different times (a week to a month) and the coefficient of variance was 5.1%. The mean and standard deviation of SOD activities of 45 blood samples from normal Japanese males 32.9 +/- 10.5 microgram per ml of blood; estimated using bovine SOD standard. The SOD activity of the fluid from lavaged lungs was 15.7 +/- 1.8 microgram/ml, and that of lung tissue homogenates from rats was 2.85 +/- 0.66 microgram/mg of protein.