Incorporation of [2−14C]mevalonic acid into phytoene by isolated chloroplasts

Josephine M. Charlton; K J. Treharne; T W Goodwin

doi:10.1042/bj1050205

Incorporation of [2−14C]mevalonic acid into phytoene by isolated chloroplasts

Biochemical Journal ◽

10.1042/bj1050205 ◽

1967 ◽

Vol 105 (1) ◽

pp. 205-212 ◽

Cited By ~ 38

Author(s):

Josephine M. Charlton ◽

K J. Treharne ◽

T W Goodwin

Keyword(s):

Ultrasonic Treatment ◽

Magnesium Chloride ◽

Mevalonic Acid ◽

Side Chain ◽

Isolated Chloroplasts

1. Chloroplasts prepared by the non-aqueous technique will, after fragmentation by ultrasonic treatment, incorporate [2−14C]mevalonic acid into phytoene, the first C40 compound formed in the biosynthetic sequence to coloured carotenoids. 2. With suspensions containing 3·5mg. of chlorophyll, the optimum amounts of cofactor required were ATP (10μmoles), magnesium chloride (20μmoles) and glutathione (20μmoles); neither NAD+ nor NADP+ was required. 3. Very small amounts of squalene are also formed and synthesis is stimulated by addition of NADH or NADPH. Phytoene synthesis was not affected by the presence of these cofactors and no lycopersene (the C40 homologue of squalene) was detected. 4. The phytol side chain of chlorophyll is also labelled under these conditions. 5. Preparations of developing chloroplasts are more active than preparations of mature chloroplasts.

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Incorporation of dl-[2−14C]mevalonic acid lactone into β-carotene and the phytol side chain of chlorophyll in cotyledons of four species of pine seedlings

Biochemical Journal ◽

10.1042/bj1050089 ◽

1967 ◽

Vol 105 (1) ◽

pp. 89-92 ◽

Cited By ~ 8

Author(s):

S. Wieckowski ◽

T W Goodwin

Keyword(s):

Mevalonic Acid ◽

Side Chain ◽

Pinus Silvestris ◽

Pine Seedlings ◽

Acid Lactone ◽

Β Carotene

1. The incorporation of dl-[2−14C]mevalonic acid lactone into β-carotene and the phytol side chain of chlorophyll has been investigated in cotyledons of four species of pine seedlings (Pinus silvestris, P. contorta, P. radiata and P. jeffrei) grown in darkness and in light. 2. The relative incorporation of label into β-carotene and the phytol side chain of chlorophyll is similar to that observed in experiments on monocotyledons and dicotyledons. 3. The relative incorporation of 14CO2 into β-carotene and phytol is much higher than the incorporation of [2−14C]mevalonic acid.

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BIOSYNTHESIS OF C19 STEROIDS FROM 4-14C-CHOLESTEROL AND 7-3H-PREGNENOLONE IN VIVO: CONSIDERATION OF NEW PATHWAYS

Acta Endocrinologica ◽

10.1530/acta.0.0400188 ◽

1962 ◽

Vol 40 (2) ◽

pp. 188-202 ◽

Cited By ~ 27

Author(s):

Shlomo Burstein ◽

Ralph I. Dorfman

Keyword(s):

Adrenal Adenoma ◽

Mevalonic Acid ◽

Compartment Model ◽

Side Chain ◽

Partition Chromatography ◽

Steroid Nucleus ◽

Single Intravenous Injection ◽

Two Compartment Model ◽

Specific Activities

ABSTRACT 3H and 14C specific activities of dehydroepiandrosterone, androsterone, 3α-hydroxy-5β-androstan-17-one and 3α-hydroxy-5α-androst-16-ene (without dilution) have been determined following a single intravenous injection of 4-14C-cholesterol and 7α-3H-pregnenolone to a virilized woman with an adrenal adenoma and massive dehydroepiandrosterone excretion. Assuming a one compartment model, or a two compartment model in which the injected radioactivity enters the compartment in which the precursor is secreted exclusively, a new pathway by which dehydroepiandrosterone is formed from cholesterol not through pregnenolone and possibly by cleavage of the side chain C-17 and C-20 is indicated. Analysis of the data by a model in which pregnenolone is secreted into two separate compartments in which progesterone and dehydroepiandrosterone are made, respectively, would explain the findings without necessitating the assumption of a new pathway. 3α-Hydroxy-5α-androst-16-ene was isolated from urine following incubation with β-glucuronidase and partition chromatography on celite suggesting that this steroid is a genuine natural product as surmised by Prelog & Ruzicka (1944) and Brooksbank & Haslewood (1950). 2-14C-Mevalonate was shown to give rise to C19 steroids which is the first in vivo demonstration that mevalonic acid is a precursor of the steroid nucleus in man.

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Studies in phytosterol biosynthesis. Mechanism of biosynthesis of cycloartenol

Biochemical Journal ◽

10.1042/bj1070417 ◽

1968 ◽

Vol 107 (3) ◽

pp. 417-426 ◽

Cited By ~ 57

Author(s):

H H Rees ◽

L J Goad ◽

T W Goodwin

Keyword(s):

Solanum Tuberosum ◽

Hydrogen Atom ◽

Mevalonic Acid ◽

Atomic Ratio ◽

Side Chain ◽

Hydrogen Migration ◽

Biosynthetic Precursor

1. The mechanism of cycloartenol biosynthesis in leaves of Solanum tuberosum was investigated with the use of [2−14C,(4R)-4−3H1]mevalonic acid. 2. The 3H/14C atomic ratio in cycloartenol was 6:6, the same as that in squalene; this eliminates lanosterol as a possible biosynthetic precursor of cycloartenol, and indicates that a hydrogen migration from C-9 to C-8 occurs. 3. Chemical isomerization of the cycloartenol to lanosterol (3H/14C ratio 5:6) and parkeol (3H/14C ratio 6:6) confirms the hydrogen migration from C-9 to C-8. 4. Possible mechanisms for the biosynthesis of cycloartenol and parkeol are discussed. 5. The 3H/14C ratio for 24-methylenecycloartanol was 6:6, demonstrating that the hydrogen atom at C-24 is retained during alkylation of the cycloartenol side chain.

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Biosynthesis of ergotamine by Claviceps purpurea (Fr.) Tul

Biochemical Journal ◽

10.1042/bj1340001 ◽

1973 ◽

Vol 134 (1) ◽

pp. 1-10 ◽

Cited By ~ 16

Author(s):

R. A. Bassett ◽

E. B. Chain ◽

K. Corbett

Keyword(s):

Amino Acid ◽

Time Course ◽

Ergot Alkaloids ◽

Mevalonic Acid ◽

Defined Medium ◽

Chemical Degradation ◽

Side Chain ◽

Claviceps Purpurea ◽

Incubation Experiments ◽

Acid Lactone

High-yielding strains of Claviceps purpurea (Fr.) Tul, grown on a defined medium, have been used for a study of the biosynthesis of the peptide ergot alkaloid, ergotamine. l-[U-14C]tryptophan, dl-[2-14C]mevalonic acid lactone, sodium [2-14C]acetate, sodium [14C]formate and the methyl group of l-[methyl-14C]methionine were efficiently incorporated into the peptide alkaloids and specifically labelled the ergoline moiety of ergotamine. These results are the same as previously found for the biosynthesis of other ergot alkaloids. Time-course incubation experiments demonstrated that l-[U-14C]phenylalanine, l-[U-14C]proline and l-[U-14C]alanine were incorporated into the peptide ergot alkaloids. Chemical degradation of the radioactive alkaloid derived from additional precursor incubation experiments showed that phenylalanine and proline function as the most efficient precursors, and specifically label the constitutive side-chain phenylalanyl and prolyl moieties of the alkaloid. The evidence obtained from l-[U-14C]alanine-incorporation experiments was inconclusive. However, degradation of ergotamine isolated after incubation with dl-[1-14C]alanine, showed that the carboxyl group of the labelled amino acid was specifically incorporated into the α-hydroxy-α-amino acid residue of the alkaloid. This, in conjunction with the l-[U-14C]alanine-incorporation results, showed conclusively that all three carbon atoms of alanine were incorporated as a biosynthetic unit into the α-hydroxy-α-amino acid moiety of ergotamine.

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Structure of Hormaomycin, a Naturally Occurring Cyclic Octadepsipeptide, in the Crystal

Zeitschrift für Naturforschung B ◽

10.5560/znb.2014-4116 ◽

2014 ◽

Vol 69 (9-10) ◽

pp. 945-949 ◽

Cited By ~ 4

Author(s):

Tim Gruene ◽

George M. Sheldrick ◽

Boris D. Zlatopolskiy ◽

Sergei I. Kozhushkov ◽

Armin de Meijere

Keyword(s):

Equatorial Plane ◽

Magnesium Chloride ◽

Side Chain ◽

Naturally Occurring ◽

Nmr Study ◽

Significant Difference

Abstract The structure of hormaomycin has been determined in two crystals grown under different conditions, i. e. in the absence and in the presence of magnesium chloride. In both crystals, the macrocyclic hexadepsipeptide assumes a rather flat conformation, and the dipeptide side chain resides in the same equatorial plane. This is a significant difference in comparison with the compact bent conformation of hormaomycin in solution, as previously determined by an extensive NMR study

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The effect of carbon monoxide on the nature of the accumulated 4,4-dimethyl sterol precursors of cholesterol during its biosynthesis from [2-14C]mevalonic acid in vitro

Biochemical Journal ◽

10.1042/bj1320439 ◽

1973 ◽

Vol 132 (3) ◽

pp. 439-448 ◽

Cited By ~ 25

Author(s):

Geoffrey F. Gibbons ◽

Konstantinos A. Mitropoulos

Keyword(s):

Gas Phase ◽

Cholesterol Biosynthesis ◽

Quantitative Difference ◽

Specific Radioactivity ◽

Mevalonic Acid ◽

Sterol Fraction ◽

Side Chain ◽

Gas Phases ◽

Physicochemical Methods

Cholesterol biosynthesis was studied in rat liver subcellular fractions incubated with dl-[2-14C]mevalonic acid under gas phases consisting of either N2+O2 (90:10) or CO+O2 (90:10). CO inhibits cholesterol biosynthesis from [2-14C]mevalonic acid and results in a large accumulation of radioactive 4,4-dimethyl sterols. Separation of the components of the 4,4-dimethyl sterol fraction showed that lanosterol and dihydrolanosterol are the major components that accumulate during cholesterol biosynthesis in an atmosphere containing CO, whereas 14-demethyl-lanosterol and 14-demethyldihydrolanosterol are the major components of the much less intensely radioactive 4,4-dimethyl sterol fraction isolated from incubations with N2+O2 as the gas phase. The identities of lanosterol, dihydrolanosterol and 14-demethyldihydrolanosterol were confirmed by both radiochemical and physicochemical methods, including g.l.c. and combined g.l.c.–mass spectrometry. CO therefore results in a qualitative as well as a quantitative difference in the 4,4-dimethyl sterol fraction which arises during cholesterol biosynthesis from mevalonic acid. The specific radioactivity of the [14C]lanosterol biosynthesized in the presence of CO was lower than that of its companion, [14C]dihydrolanosterol. The relative amounts of 4,4-dimethyl-Δ24-sterols and 4,4-dimethyl-24,25-dihydrosterols present in each type of incubation suggest that enzymic reduction of the sterol side chain occurs predominantly at a stage after that of lanosterol.

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