We have measured rates of ketogenesis and malonyl-CoA contents of hepatocytes isolated from meal-fed rats under a variety of incubation conditions in order to determine the relationship between the intracellular malonyl-CoA level and the rate of ketogenesis. Evidence obtained from rat liver homogenates suggested that malonyl-CoA, which is a major determinant of fatty acid synthesis in vivo, als...

Coenzyme M is an essential coenzyme for methanogenesis. The proposed biosynthetic pathway consists of five steps, of which the fourth step is catalyzed by sulfopyruvate decarboxylase (ComDE). Disruption of the gene comE by transposon mutagenesis resulted in a partial coenzyme M auxotroph, which grew poorly in the absence of coenzyme M and retained less than 3% of the wild type level of coenzyme...

The fatty acid synthetase of pigeon liver catalyzes the conversion of acetyland malonyl-coenzyme A to long chain saturated fatty acids in the presence of reduced nicotinamide adenine dinucleotide phosphate. The major product of the reaction is palmitic acid, but small amounts of other long chain fatty acids are also formed. The over-all reaction for the synthesis of palmitic acid is: 1 acetyl-C...

Acetyl-coenzyme A carboxylase (ACCase) catalyzes the formation of malonyl-coenzyme A, which is used in the plastid for fatty acid synthesis and in the cytosol for several pathways including fatty acid elongation and flavonoid synthesis. Two overlapping Arabidopsis genomic clones were isolated and sequenced to determine the entire ACCase-coding region. Thirty introns with an average size of 94 b...

Fatty acids (FAs) are essential constituents of cell membranes, signaling molecules, and bioenergetic substrates. Because CD8(+) T cells undergo both functional and metabolic changes during activation and differentiation, dynamic changes in FA metabolism also occur. However, the contributions of de novo lipogenesis to acquisition and maintenance of CD8(+) T cell function are unclear. In this ar...

Previous communications from this laboratory have established the function of pyridoxine derivatives' in the tyrosine decarboxylase system of Streptococcus faecalis, and a synthetic medium has been described for the production of cells active in this function (Bellamy and Gunsalus, 1943, 1944). Cells grown in media deficient in,pyridoxine derivatives have been shown to contain the tyrosine deca...

molecular modeling analysis of charge density and heat of fornation by pm3 method as well as c, h nmr and 2d-nmr measurements of histidine (substrate) and some of its derivatives as histidine decarboxylase inhibitors were performed. it was established that the atom, usually nitrogen, which forms internal aldimine with pyridoxal5 -phosphate (plp), (coenzyme), has negative and almost equal charge...

As theophylline is known to stimulate lipolysis and lipid mobilisation, plasma concentrations of malonyl dialdehyde were studied in asthmatic patients being treated with sustained release theophylline. Malonyl dialdehyde was assessed as malonyl dialdehyde like material (MDA-LM) by the thiobarbituric acid assay. In a kinetic study (eight patients) plasma MDA-LM concentrations were found to be si...

The 3-hydroxypropionate cycle is a new autotrophic CO(2) fixation pathway in Chloroflexus aurantiacus and some archaebacteria. The initial step is acetyl-coenzyme A (CoA) carboxylation to malonyl-CoA by acetyl-CoA carboxylase, followed by NADPH-dependent reduction of malonyl-CoA to 3-hydroxypropionate. This reduction step was studied in Chloroflexus aurantiacus. A new enzyme was purified, malon...

The sensitivity of carnitine palmitoyl coenzyme A (CoA) transferase I to inhibition of its activity by malonyl-CoA is progressively reduced in mitochondria isolated from ischemic cardiac cells as blood flow decreases to 30% or less of the preocclusion flow. The activity of carnitine palmitoyl-CoA transferase I in mitochondria isolated from nonischemic cardiac cells demonstrates incomplete inhib...