Carotenoids in relation to mitochondria

• Main Author: West, Sylvia
• Published: Royal Holloway, University of London 1968
• Subjects: 571.6; Biochemistry
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.704026

The location of carotenoids in mitochondria is poorly documented in the literature. Therefore, initially, plant and animal tissues and a microbial culture were examined to determine whether carotenoids were situated in mitochondria and subsequently a physiological reaction of plant mitochondria, in which the participation of carotenoids may be implicated, was investigated. To establish the presence of carotenoids in mitochondria of cauliflower buds, heart muscle, and the yeast Rhodotorula rubra the carotenoid content of arbitrary centrifugal fractions was compared with their mitochondrial enzyme activity. Cauliflower bud tissue, which contained the carotenoids B-carotene, lutein, violaxanthin, and neoxanthin, was fractionated both by differential and discontinuous sucrose density gradient centrifugation. A correlation was observed between the sedimentation patterns of carotenoid-containing particles and mitochondria, marked by succinic dehydrogenase, when lipoxidase-catalysed carotenoid oxidation and the production of a material which absorbed ultra violet light were inhibited. Ox heart contained two types of carotenoid. One appeared to originate from the blood and could be degraded by incubation at 0° C following haemolysis. In its absence, the second type of carotenoid, composed of a- and B -carotene and a xanthophyll, was present in particles which sedimented in the same manner as the mitochondria. Carotenoid was not detected in pig heart, however. The presence of excess extra mitochondrial carotenoid in the yeast Rhodotorula rubra masked the possible presence of mitochondrial carotenoids. Illumination was observed to decrease the rate of respiration of cauliflower bud mitochondria after protection from the light for 60 minutes. However, the period of protection was reduced by preincubation with the centrifugal supernatant, preillumination, and the action of a lipoxidase preparation on exogenous ammonium linoleate in the assay medium. Exogenous carotenoid restored protection to mitochondria from old cauliflowers and safeguarded respiration against loss of protection caused by lipoxidase activity.