Studies on the catalyzed interconversions of vitamin A derivatives

Journal Article · Wed May 04 00:00:00 EDT 1983 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00347a058· OSTI ID:5536211

Rando, R R; Chang, A

The kinetics of I/sub 2/-catalyzed isomerization of the retinal isomers were studied. The all-trans isomer formed 13-cis-retinal rapidly with a rate constant of 1.9 X 10/sup -4/ s/sup -1/. The reverse reaction occurred with a rate constant of 4.5 X 10/sup -4/ s/sup -1/. The 11-cis isomer was first converted to all-trans-retinal with a rate constant of 3.1 X 10/sup -4/ s/sup -1/, although the 13-cis isomer was also rapidly formed. The 9-cis isomer was isomerized to the 9-cis, 13-cis isomer before the other isomers were generated and the 13-cis isomer was converted to its all-trans congener prior to the formation of the other isomers. Similar results appear to occur when other methods of catalysis are used. This isomerization about the C/sub 13/-C/sub 14/ doubled bond appears to be a kinetically favored event, eliminating the possibility that 11-cis might be a kinetic product formed from the all-trans isomer. At equilibrium, only 0.1% of 11-cis-retinal is found. Equilibration of all-trans-retinol palmitate also generated very little of the 11-cis isomer (less than or equal to0.2%) 11-cis-retinol palmitate at equilibrium. The implications of these results for an 11-cis-retinal regeneration mechanism in the eye are discussed.

• Research Organization: Harvard Medical School, Boston, MA
• OSTI ID: 5536211
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 105:9; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
550200 -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
BODY
BODY AREAS
CATALYSIS
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
ELEMENTS
EYES
FACE
HALOGENS
HEAD
IODINE
ISOMERIZATION
KINETICS
NONMETALS
ORGANS
REACTION KINETICS
RETINA
SENSE ORGANS
VITAMIN A
VITAMINS