Enzymatic synthesis of carotenes by cell-free preparations of fruit of several genetic selections of tomatoes

Papastephanou, Constantin; Barnes, Francis J.; Briedis, Anita V.; Porter, John W.

doi:10.1016/0003-9861(73)90657-7

Cited by 25 publications

(5 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Conversion of labeled lycopene to mono-and dicyclic carotenes was demonstrated by soluble enzymes from tomato fruit plastids Papastephanou et al, 1973).…”

Section: Formation Of Cyclic Carotenesmentioning

confidence: 99%

Pigments in Vegetables

Gross¹

1991

243

View full text Add to dashboard Cite

“…Conversion of labeled lycopene to mono-and dicyclic carotenes was demonstrated by soluble enzymes from tomato fruit plastids Papastephanou et al, 1973).…”

Section: Formation Of Cyclic Carotenesmentioning

confidence: 99%

Pigments in Vegetables

Gross¹

1991

243

View full text Add to dashboard Cite

“…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.…”

Section: Preparation Of Radioactive Substrates Cis-[ 14c]phytoenementioning

confidence: 99%

“…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).…”

Section: Preparation Of Radioactive Substrates Cis-[ 14c]phytoenementioning

confidence: 99%

“…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.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Sc¹,

Kates²,

Jw³

1976

Can. J. Biochem.

Self Cite

View full text Add to dashboard Cite

[14C]Mevalonate or (14C)isopentenyl pyrophosphate was found to be converted to transphytoene, trans-phytofluene, lycopene, and beta-carotene by a cell-free 270 000 X g supernatant fraction prepared from Halobacterium cutirubrum cells that were broken by manual grinding with glass beads. Incubations were done under N2 in the dark at 37 degrees C in 4 M NaCl in presence of FAD, NADP, and MgCl2; ATP was also added when mevalonate was the substrate. This system was also capable of converting trans-(14C)phytoene to beta-carotene via the intermediates trans-phytofluene, zeta-carotene, neurosporene, lycopene, and gamma-carotene. Each of these labelled intermediates on incubation separately with the same enzyme system was shown to be converted to the intermediates farther down the pathway. The results of this study show that the biosynthetic pathway for the formation of C40 carotenes in H. cutirubrum proceeds as follows: isopentenyl pyrophosphate leads to trans-phytoene leads to trans-phytofluene leads to zeta-carotene leads to neurosporene leads to lycopene leads to gamma-carotene leads to beta-carotene. This pathway differs from that in higher plants in that the cis isomers of phytoene and phytofluene are not on the main pathway of carotene biosynthesis, as they are in higher plants. Furthermore, trans-phytoene, which has not been reported to have any role in higher plants, appears to be the main intermediate in carotene biosynthesis in H. cutirubrum.

show abstract

“…Evidence has been presented for both neurosporene and lycopene as the precursors of the cyclic carotenoids (see Porter & Anderson, 1967; Goodwin, 1971). Direct demonstration of the conversion of lycopene to /3-carotene has been made using spinach-chloroplast and fruit-plastid preparations (Kushwaha, Subbarayan, Beeler & Porter, 1969; Papastephanou, Barnes, Briedis & Porter, 1973). Cyclization of lycopene has also been indicated from inhibitor experiments while cyclization of neurosporene has only been demonstrated in fungi (see Davies, 1975).…”

Section: (3) Conversion Of Phytoene To Carotenoidsmentioning

confidence: 99%

Biosynthesis of Small Molecules in Chloroplasts of Higher Plants

Givan

Harwood

1976

Biological Reviews

View full text Add to dashboard Cite

Summary 1. Chloroplasts of higher plants contain enzymes which permit them to synthesize many kinds of small molecules in addition to carbohydrates. 2. Either aqueous or non‐aqueous techniques may be used to isolate chloroplasts. Aqueous methods permit the isolation of chloroplasts showing high rates of photosynthesis; the organelles can be purified by means of density gradients. Non‐aqueously isolated chloroplasts cannot photosynthesize, but show good retention of low‐molecular‐weight substances and soluble enzymes. 3. Whole cells photoassimilating 14CO2 show considerable formation of 14C‐labelled amino acids and lipids, but isolated chloroplasts exhibit very poor synthesis of amino acids and lipids from 14CO2. 4. Chloroplasts play an important rôle in reducing nitrate to ammonia. There is controversy about the presence in chloroplasts of nitrate reductase and about the mechanism of the light‐dependent reduction of nitrate to nitrite; however, it is generally agreed that non‐cyclic electron transport directly supports reduction of nitrite to ammonia via a chloroplastic nitrite reductase. 5. Chloroplasts actively assimilate inorganic nitrogen into amino acids. The assimilation reaction is either the reductive amination of α‐ketoglutarate to glutamate or the ATP‐dependent conversion of glutamate to glutamine. The enzyme glutamate synthase has recently been found to be present in chloroplasts and may play an important function in nitrogen assimilation. 6. Numerous transaminases (aminotransferases) are present in chloroplasts. 7. The source of α‐keto‐acid precursors of chloroplastic amino acids is unknown. It remains to be established whether chloroplasts import the required keto acids or whether some of them might be generated via an incomplete tricarboxylic‐acid cycle located in the chloroplast. 8. Chloroplasts contain characteristically high levels of mono and digalactosyl diglycerides, sulpholipid and phosphatidyl glycerol. They also have large amounts of polyunsaturated fatty acids. 9. Fatty acids are synthesized by the concerted action of fatty‐acid synthetase, elongases and desaturases. Two pathways have been implicated for the formation of α‐linolenic acid. 10. The galactosyldiglycerides are synthesized by successive galactosylation of diglyceride. The enzymes responsible are probably located in the chloroplastic envelope. 11. The other major chloroplastic acyl lipids (sulpholipid, phosphatidylglycerol and phosphatidylcholine) have not been, as yet, synthesized de novo by means of isolated chloroplast fractions. However, indirect evidence indicates that the first two are probably formed there. 12. Chlorophyllide synthesis involves the formation of δ‐aminolaevulinic acid (δALA) followed by conversion of δALA to protoporphyrin IX, which is then transformed into protochlorophyll. 13. Recent evidence favours the view that δALA synthesis is not mediated by δALA synthetase but by another pathway in which δALA can be derived from α‐ketoglutarate or glutamate. It has not been established whether this pathway is loca...

show abstract

Enzymatic synthesis of carotenes by cell-free preparations of fruit of several genetic selections of tomatoes

Cited by 25 publications

References 18 publications

Pigments in Vegetables

Pigments in Vegetables

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

Biosynthesis of Small Molecules in Chloroplasts of Higher Plants

Contact Info

Product

Resources

About

Enzymatic synthesis of carotenes by cell-free preparations of fruit of several genetic selections of tomatoes

Cited by 25 publications

References 18 publications

Pigments in Vegetables

Pigments in Vegetables

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

Biosynthesis of Small Molecules in Chloroplasts of Higher Plants

Contact Info

Product

Resources

About

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