The enzymatic cleavage of beta-carotene: still controversial

The enzyme beta-carotene-15,15'-dioxygenase from guinea pig intestinal mucosa was found to cleave beta-carotene and produce 2 mol of retinal for 1 mol of beta-carotene. However, extensive evidence exists also for random (excentric) cleavage, resulting in retinoic acid and retinal, with a preponderance of apocarotenals formed as intermediates.