Sterol biosynthesis from (3RS,2R)-[2-14C,2-3H]mevalonic acid in a yeast homogenate. Stereochemistry of the C-15 tritium atom

1974 ◽  
Vol 96 (26) ◽  
pp. 8107-8108 ◽  
Author(s):  
E. Caspi ◽  
J. P. Moreau ◽  
P. J. Ramm
Keyword(s):  
Mevalonic Acid ◽  
Sterol Biosynthesis ◽  
Tritium Atom ◽  
Yeast Homogenate

scholarly journals Sterol biosynthesis in the echinoderm Asterias rubens

1975 ◽  
Vol 146 (1) ◽  
pp. 25-33 ◽  
Author(s):  
A G Smith ◽  
L J Goad
Keyword(s):  
Body Wall ◽  
De Novo ◽  
Mevalonic Acid ◽  
The Body ◽  
Sterol Biosynthesis ◽  
Asterias Rubens ◽  
Nonsaponifiable Lipid ◽  
Major Sterol ◽  
Dietary Origin ◽  
Isolated Tissues

1. [2(-14)C]Mevalonic acid injected into the echinoderm Asterias rubens (Class Asteroidea) was effectively incorporated into the non-saponifiable lipid. 2. The most extensively labelled compounds were squalene and the 4,4-dimethyl sterols with much lower incorporations into the 4α-monomethyl and 4-demethyl sterol fractions. 3. Labelled compounds identified were squalene, lanosterol, 4,4-dimethyl-5α-cholesta-8,24-dien-3β-ol and 4α-methyl-5α-cholest-7-en-3β-ol; these are all intermediates in sterol biosynthesis. 4. The major sterol in A. rubens, 5α-cholest-7-en-3β-ol, was also labelled showing that this echinoderm is capable of sterol biosynthesis de novo. 5. No evidence was obtained for the incorporation of [2(-14)C]mevalonic acid into the C28 and C29 components of the 4-demethyl sterols or 9β,19-cyclopropane sterols found in A. rubens and it is assumed that these sterols are of dietary origin. 6. Another starfish Henricia sanguinolenta also incorporated [2(-14)C]mevalonic acid into squalene and lanosterol. 7. Various isolated tissues of A. rubens were all capable of incorporation of [2(-14)C]mevalonic acid into the nonsaponifiable lipid. With the body-wall and stomach tissues radioactivity accumulated in squalene and the 4,4-dimethyl sterols, but with the gonads and pyloric caecae there was a more efficient incorporation of radioactivity into the 4-demethyl sterols, principally 5α-cholest-7-en-3β-ol.

scholarly journals Incorporation of [2−14C,(5R)-5−3H1]mevalonic acid into cholesterol by a rat liver homogenate and into β-sitosterol and 28-isofucosterol by Larix decidua leaves

1969 ◽  
Vol 114 (4) ◽  
pp. 885-892 ◽  
Author(s):  
L J Goad ◽  
G. F. Gibbons ◽  
Loretta M. Bolger ◽  
H H Rees ◽  
T W Goodwin
Keyword(s):  
Double Bond ◽  
Hydrogen Atom ◽  
Rat Liver ◽  
Cholesterol Biosynthesis ◽  
Liver Homogenate ◽  
Mevalonic Acid ◽  
Atomic Ratio ◽  
Larix Decidua ◽  
Tritium Atom

1. Incubation of a rat liver homogenate with 3R-[2−14C,(5R)-5−3H1]mevalonic acid gave cholesterol with 3H/14C atomic ratio 6:5. 2. Conversion of the labelled cholesterol into 3β-acetoxy-6-nitrocholest-5-ene or cholest-4-ene-3,6-dione resulted in the loss of one tritium atom from C-6. 3. These results show that during cholesterol biosynthesis the 6α-hydrogen atom of a precursor sterol is eliminated during formation of the C-5–C-6 double bond. 4. Incorporation of 3R-[2−14C,(5R)-5−3H1]mevalonic acid into the sterols of larch (Larix decidua) leaves gave labelled cycloartenol and β-sitosterol with 3H/14C atomic ratios 6:6 and 6:5 respectively. 5. One tritium atom was lost from C-6 on conversion of the labelled β-sitosterol into either 3β-acetoxy-6-nitrostigmast-5-ene or stigmast-4-ene-3,6-dione, demonstrating that formation of the C-5–C-6 double bond of phytosterols also involves the elimination of the 6α-hydrogen atom of a precursor sterol. 6. The 3R-[2−14C,(5R)-5−3H1]mevalonic acid was also incorporated by larch (L. decidua) leaves into a sterol that co-chromatographed with 28-isofucosterol. Confirmation that the radioactivity was associated with 28-isofucosterol was obtained by co-crystallization with carrier 28-isofucosterol and ozonolysis of the acetate to give radioactively labelled 24-oxocholesteryl acetate. 7. The significance of these results to phytosterol biosynthesis is discussed.

scholarly journals Sterol biosynthesis by the sea urchin Echinus esculentus

1974 ◽  
Vol 142 (2) ◽  
pp. 421-427 ◽  
Author(s):  
Andrew G. Smith ◽  
L. John Goad
Keyword(s):  
Sea Urchin ◽  
Mevalonic Acid ◽  
Small Extent ◽  
Sterol Biosynthesis

1. The 4-demethyl sterols of Echinus esculentus consisted of cholesterol as the major component, with lower concentrations of nine other C26, C27, C28 and C29 Δ5sterols. 2. [2-14C]Mevalonic acid was readily incorporated by the urchin into squalene, lanosterol and desmosterol but only to a small extent into cholesterol. 3. [26-14C]Desmosterol did not appear to be reduced to give cholesterol, but conversion of 5α-[2-3H2]lanost-8-en-3β-ol into cholesterol was observed. 4. No C-24 dealkylation of [4-14C]sitosterol or metabolism of [4-14C]cholesterol could be detected.

Sign in / Sign up

Export Citation Format

Share Document