passages.id: split_4_test_1579_passage
passages.type: progene_text
passages.text: Here we report the identification of a cDNA from mouse encoding a second type of carotene dioxygenase catalyzing exclusively the asymmetric oxidative cleavage of beta-carotene at the 9 ' , 10 ' double bond of beta-carotene and resulting in the formation of beta-apo-10'-carotenal and beta-ionone , a substance known as a floral scent from roses , for example .