Abstract
Cinnabarinate synthase was purified from the nuclei of baboon liver. Two purified fractions were obtained that exhibited a typical heme protein absorption spectrum; a probable identity with catalase was demonstrated. It was confirmed that catalase in the presence of Mn2+ produces cinnabarinate from 3-hydroxyanthranilate [both substrate and product are carcinogenic in experimental animals]. The existence of a distinct cinnabarinate synthase enzyme is doubtful.