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A study of the biosynthesis of sterols and related compounds by a bovine aorta preparation

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Title A study of the biosynthesis of sterols and related compounds by a bovine aorta preparation
Names Walsh, Marilyn Ruth (creator)
Gamble, Wilbert (advisor)
Date Issued 1967-08-17 (iso8601)
Note Graduation date: 1968
Abstract Previous investigations of the biosynthesis of sterols by the
arterial wall have shown that the intact aorta is capable of low level
incorporation of labeled precursor into a sterol digitonide. The biosynthesis
of sterols and related lipids by a cell-free preparation of
bovine aorta was investigated in the present study.
The cell-free system was the 60,000 x g supernatant of a Waring
Blendor homogenate of aorta and 0.1 M phosphate nicotinamide
buffer. When the 60,000 x g supernatant was incubated in the presence
of adenosine triphosphate and mevalonic acid-2-C¹⁴, the non-saponifiable
fraction (NSF) of the incubation mixture was radioactive.
Acetate-2-C¹⁴ was not incorporated into the NSF. A sterol digitonide
of low specific activity (60 to 237 counts per min per mg cholesterol)
could be isolated from the NSF, but the major amount of radioactivity in the NSF was not digitonin precipitable.
The 60,000 x g supernatant was capable of forming phosphomevalonic
acid, mevalonic acid pyrophosphate, and isopentenyl pyrophosphate
from MVA.
Chromatography of the NSF on silicic acid-celite columns
showed the labeled material to be slightly less polar than cholesterol.
Samples of the labeled material isolated (by preparative layer chromatography)
from large amounts of NSF did not give a positive Liebermann-Burchard reaction and did not form a 2, 4-dinitrophenylhydrazone.
On silver nitrate impregnated layers of silicic acid, the labeled
material appeared to be chromatographically similar to farnesol and squalene.
Gas chromatography of a sample of labeled material showed all
the radioactivity present in one peak with a retention time intermediate
between the retention times of farnesol and squalene. The mass
spectrum of the labeled material indicated the presence of compounds
with m/e of 380, 384, and 386.
The results of these experiments indicated that the major biosynthetic
product is not cholesterol or other similar sterol, but may
be a "prenol" of some kind.
Genre Thesis/Dissertation
Topic Steroids
Identifier http://hdl.handle.net/1957/47072

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