Abstract
We examined the effects of linoleic acid on the activities of rat small intestinal mucosa β- carotene 15,15’-monooxygenase (BCO1) and recombinant murine BCO1. When β-carotene was the substrate, the activity of the mucosal BCO1 with 1 mM linoleic acid was higher than that without linoleic acid. When β-cryptoxanthin was the substrate, the activity of the mucosal BCO1 was not changed by the addition of linoleic acid. When β-carotene was the substrate, the activity of a mixture of recombinant BCO1 and the mucosal BCO1 was lower than the sum of the activity of each BCO1. However, in the presence of linoleic acid, the activity of the mixture of both BCO1s was higher than the sum of the activity of each BCO1. When β-cryptoxanthin was the substrate, the activity of the mixture of both BCO1s was higher than the sum of the activity of each BCO1. These results suggest that when β-carotene is the substrate, BCO1 is inhibited by intestinal mucosa components, but this inhibition of BCO1 activity by intestinal mucosa components could be released by the addition of linoleic acid to the mixture. These results also suggest that BCO1 activity is stimulated by intestinal mucosa components when β-cryptoxanthin is the substrate.
