This picture shows one of the step of heme synthesis. In this step, two propanoate groups of Coproporhyrinogen III are decarboxylated to from protoporphyrinogen IX. The enzyme used is oxidase. Oxidase enzymes catalyze the removal of hydrogen in the presence of oxygen to from water or hydrogen peroxide.
So, will a water molecule form in this step. 2H+ will come from the two carboxylic groups and oxygen will combine with it to form water. Will water molecule form in this way?