The enzymatic conversion of cis-[14C]phytofluene, trans-[14C]phytofluene, and trans-ζ-[14C]carotene to poly-cis-acyclic carotenes by a cell-free preparation of tangerine tomato fruit plastids

Enzymatic synthesis of C40 carotenes by cell-free preparation from Halobacterium cutirubrum

“…Our results ( Table 2) indicate that cis isomers of phytoene and phytofiuene act as very poor precursors as compared with their trans isomers. The results reported in this paper thus show that the biosynthetic pathway for the formation of C40 carotenes in W. cutirubrum is similar in several respects to that in higher plants (13,16,24). However, it differs from the latter in that the cis isomers of phytoene and phytofluene do not appear to be direct intermediates in the main pathway of carotene biosynthesis in H. c~ctirubrum.…”

“…cis Carotens These were prepared biosynthetically from 1-[I4C]-isopentenyl pyrophosphate using the enzyme system prepared from the lyophilized plastids of red tomatoes as described by Porter and co-workers (14)(15)(16). The radioactive carotene products were isolated and purified by column chromatography at least three times on alumina followed by thin-layer chromatography on silica gel G, as described in references 11-16. The radiochemical purity of all the above radioactive substrates was established unequivocally by cochromatography with authentic nonradioactive samples on an alumina column and on silica gel and alumina thin-layer plates, and also by gas-liquid chromatography of the perhydrogenated substrates, as described below (see Refs.…”

“…The radioactive carotene products were isolated and purified by column chromatography at least three times on alumina followed by thin-layer chromatography on silica gel G, as described in references 11-16. The radiochemical purity of all the above radioactive substrates was established unequivocally by cochromatography with authentic nonradioactive samples on an alumina column and on silica gel and alumina thin-layer plates, and also by gas-liquid chromatography of the perhydrogenated substrates, as described below (see Refs. [12][13][14][15][16]. The concentrations of the substrates purified by chromatography on alumina were determined by spectrophotometric assay (19).…”

“…T h e biosynthetic pathway for C4, carotenes in higher plants has been shown (9)(10)(11)(12)(13)(14)(15)(16) p-carotene (&@-carotene). A similar pathway has also been proposed for a few fungi, Meurtsspora c m s s u and Phycontyces bkakc.skseanus (17, I$), but n o such information is available concerning the biosynthesis sf C,, carotenes in a halophilic bacterium.…”

Effect of nicotine on biosynthesis of C50 carotenoids in Halobacterium cutirubrum

“…In addition, small amounts s f C,, carotenes have also been found to occur in this and other halophiles (2,3). The biosynthetic pathway for C,,-carotene hydrocarbons in higher plants (4)(5)(6) and a few other organisms (7) has been elucidated in the last 10 years. In the accompanying paper in this issue, we report on the biosynthesis of C40 carotenes in Halobacterium cudiruhrurn by cell-free preparations and propose a pathway for their formation in this organism (8).…”