The kinetic mechanism of pigeon liver fatty acid synthetase action has been studied using steady state kinetic analysis. Initial velocity studies are consistent with an earlier suggestion that the enzyme catalyzes this reaction by a seven-site ping-pong mechanism. Although the range of substrate concentrations that could be used was limited by several factors, the initial velocity patterns show...

METHODS Figures have been published showing the variation of velocity of decarboxylation with' the concentration of codecarboxylase for a given amount of apo-enzyme in the cases of l(+)-lysine decarboxylase (Gale & Epps, 1944) and of 1( )-tyrosine decarboxylase (Epps, 1944). In either case the velocity of decarboxylation bears an approximately linear relation to the amount of codecarboxylase ad...

Coenzyme A is required for many synthetic and degradative reactions in intermediary metabolism and is the principal acyl carrier in prokaryotic and eukaryotic cells. Coenzyme A is synthesized in five steps from pantothenate, and recently the CoaA biosynthetic genes in bacteria and human have all been identified and characterized. Coenzyme A biosynthesis in plants is not fully understood, and to...

Increased accumulation of fatty acids and their derivatives can impair insulin-stimulated glucose disposal by skeletal muscle. To characterize the nature of the defects in lipid metabolism and to evaluate the effects of thiazolidinedione treatment, we analyzed the levels of triacylglycerol, long-chain fatty acyl-coA, malonyl-CoA, fatty acid oxidation, AMP-activated protein kinase (AMPK), acetyl...

Pseudomonas putida is able to grow on malonate as a sole source of carbon and energy. Malonate decarboxylase is a key enzyme catabolizing malonate to acetate and CO2. The enzyme consists of the five different subunits, (60 kDa), (33 kDa), (28 kDa), (13 kDa), and (30 kDa). The smallest subunit is an acyl-carrier protein (ACP) possessing 2'-(5"-phosphoribosyl)-3'-dephospho-CoA as a prosthetic gro...

Liver acetyl-CoA carboxylase, a biotin-enzyme which catalyzes the ATP-dependent carboxylation of acetyl-CoA (acceptor) to form malonyl-CoA (carboxylated acceptor), decarboxylates malonyl-CoA by a biotin-dependent, as well as a biotin-independent mechanism. Neither ADP, Pi, nor divalent metal ion are required for either of these abortive decarboxylations. The biotin-dependent reaction is blocked...

Mammalian histidine decarboxylases have not been characterized well owing to their low amounts in tissues and instability. We describe here the first spectroscopic characterization of a mammalian histidine decarboxylase, i.e. a recombinant version of the rat enzyme purified from transformed Escherichia coli cultures, with similar kinetic constants to those reported for mammalian histidine decar...

Acute increases in the concentration of malonyl CoA play a pivotal role in mediating the decrease in fatty acid oxidation that occurs in many tissues during refeeding after a fast. In this study, we assess whether such increases in malonyl CoA in liver could be mediated by malonyl CoA decarboxylase (MCD), as well as acetyl CoA carboxylase (ACC). In addition, we examine how changes in the activi...

The identification of optimal genotypes that result in improved production of recombinant metabolites remains an engineering conundrum. In the present work, various strategies to reengineer central metabolism in Escherichia coli were explored for robust synthesis of flavanones, the common precursors of plant flavonoid secondary metabolites. Augmentation of the intracellular malonyl coenzyme A (...