a carotenoid beta-end derivative + 2 A <=> a carotenoid chi-end derivative + 2 AH2
a carotenoid beta-end derivative + 2 a <=> a carotenoid chi-end derivative + 2 ah2
a carotenoid beta-end derivative + 2 A <=> a carotenoid chi-end derivative + 2 AH2
a carotenoid beta-end derivative + 2 a <=> a carotenoid chi-end derivative + 2 ah2