On the mechanism of peroxidase-catalyzed chemiluminescence from isobutyraldehyde.

The reaction of isobutyraldehyde with dissolved oxygen catalyzed by horseradish peroxidase has been studied from the standpoint of determining the rate-limiting factor under a variety of conditions. Chemiluminescence from the product triplet acetone and rate of oxygen uptake were determined in simultaneous experiments. The reaction is initiated by the peracid obtained from the uncatalyzed autoxidation of the aldehyde; and under certain conditions the amount of peracid is also rate-limiting in the steady-state portion of the reaction. Under other conditions the total amount of enzyme and under still others the rate of formation of enol from the parent aldehyde controls the rate.