A method for measuring the rate of total daily cholesterol synthesis in man has been developed through isotope kinetic studies of squalene biosynthesis after intravenous administration of [14C]mevalonic acid. Plasma squalene becomes rapidly labeled, reaching maximal specific activity approximately 100 min after mevalonate administration and then decays exponentially to reach undetectable levels...

Patients with coeliac disease have a greatly enhanced whole body synthesis of cholesterol, but its origin is not known. In this paper the synthesis and concentrations of cholesterol and its precursors, squalene and methyl sterols, were studied in jejunal biopsies from healthy volunteers and adult patients with coeliac disease. The incorporation rates of 14C-acetate and 3H-mevalonate into non-sa...

We have recently presented evidence indicating that during biosynthesis of squalene from farnesyl pyrophosphate by rat liver microsomes, 1 hydrogen atom attached to carbon 1 of 1 of the 2 precursor molecules condensing to squalene was exchanged for a hydride ion derived from reduced triphosphopyridine nucleotide (1). This conclusion was drawn from the observations, (a) that during synthesis of ...

Since deodorization distillate, a by-product of rice bran oil production, contains squalene (ca. 8%) and phytosterols (ca. 4%) as unsaponifiable components, the concentration of those materials for their use in the cosmetics and food industries is desirable. In the present work, a novel fractionation method of concentrating squalene and phytosterols from deodorization distillate or the unsaponi...

In the violaxanthin cycle, the violaxanthin de-epoxidase and zeaxanthin epoxidase catalyze the inter-conversion between violaxanthin and zeaxanthin in both plants and green algae. The zeaxanthin epoxidase gene from the green microalga Chlorella zofingiensis (Czzep) has been isolated. This gene encodes a polypeptide of 596 amino acids. A single copy of Czzep has been found in the C. zofingiensis...

Several mechanisms that utilize farnesyl pyrophosphate and nerolidyl pyrophosphate as condensing substrates have been postulated for the asymmetric condensation reaction in squalene biosynthesis. Although there is ample evidence that farnesyl pyrophosphate is a substrate for this reaction, there has been no information concerning the role of nerolidyl pyrophosphate. We have made the following o...

Human sebum contains squalene, which is a polyunsaturated triterpenoid hydrocarbon (2, 7). This substance constitutes approximately 5 per cent of skin surface sebum of the adult (2). Oxygen is taken up avidly when squalene is ex posed to air, with the rapid formation of peroxides. This fact suggested that it might function as a protective agent in sebum. It has been demon strated that it is fun...