472-93-5Relevant articles and documents
Plant carotene cis-trans isomerase CRTISO: A new member of the FAD red-dependent flavoproteins catalyzing non-redox reactions
Yu, Qiuju,Ghisla, Sandro,Hirschberg, Joseph,Mann, Varda,Beyer, Peter
experimental part, p. 8666 - 8676 (2012/03/08)
The carotene cis-trans isomerase CRTISO is a constituent of the carotene desaturation pathway as evolved in cyanobacteria and prevailing in plants, in which a tetra-cis-lycopene species, termed prolycopene, is formed. CRTISO, an evolutionary descendant of the bacterial carotene desaturase CRTI, catalyzes the cis-to-trans isomerization reactions leading to all-trans-lycopene, the substrate for the subsequent lycopene cyclization to form all-trans-α/ β-carotene. CRTISO and CRTI share a dinucleotide binding motif at the N terminus. Here we report that this site is occupied by FAD in CRTISO. The reduced form of this cofactor catalyzes a reaction not involving net redox changes. Results obtained with C(1)- and C(5)-deaza-FAD suggest mechanistic similarities with type II isopentenyl diphosphate: dimethylallyl diphosphate isomerase (IDI-2). CRTISO, together with lycopene cyclase CRTY and IDI-2, thus represents the third enzyme in isoprenoid metabolism belonging to the class of non-redox enzymes depending on reduced flavin for activity. The regional specificity and the kinetics of the isomerization reaction were investigated in vitro using purified enzyme and biphasic liposome-based systems carrying specific cis-configured lycopene species as substrates.Thereaction proceeded from cis to trans, recognizing half-sides of the symmetrical prolycopene and was accompanied by one trans-to-cis isomerization step specific for the C(5)-C(6) double bond. Rice lycopene β-cyclase (OsLCY-b), when additionally introduced into the biphasic in vitro system used, was found to be stereospecific for all-trans-lycopene and allowed the CRTISO reaction to proceed toward completion by modifying the thermodynamics of the overall reaction.
A novel, selective, and efficient route to carotenoids and related natural products via Zr-catalyzed carboalumination and Pd- and Zn-catalyzed cross coupling.
Zeng,Negishi
, p. 719 - 722 (2007/10/03)
[structure: see text]. A highly efficient and stereoselective protocol for the syntheses of symmetrical and unsymmetrical carotenoids involving Zr-catalyzed carboalumination of conjugated oligoenynes and Pd- and Zn-catalyzed alkenyl-alkenyl coupling has been developed and applied to the syntheses of beta- and gamma-carotene and vitamin A. gamma-Carotene of > or =99% isomeric purity was prepared in three linear steps (five steps overall) from beta-ionone, enyne 8, (E)-ICH=CHBr, and (E)-Me3SiC triple bond CCH=CHBr in 32% overall yield.
Synthesen von Carotinen mit ψ-Endgruppen und (Z)-Konfiguration an terminalen konjugierten Doppelbindungen
Zumbrunn, Albrecht,Uebelhart, Peter,Eugster, Conrad Hans
, p. 1519 - 1539 (2007/10/02)
Five carotenes bearing (5Z)-ψ-end groups were synthesized and carefully characterized: (5Z)-lycopene (6), (5Z,5'Z)-lycopene (7), (5'Z)-neurosporene (8), (5'Z)-β,ψ-carotene (12), and (5'Z)-εψ-carotene (14).
