(R)and (S)-Z-deuteriopropionyl coenzyme A of approximately 75% optical purity were prepared by a series of reactions starting from optically pure alanine. With these compounds as substrates for propionyl-CoA carboxylase, the deuterium isotope effect was found to be small and probably secondary. No tritium isotope effect was observed when enzymatically prepared 2-3H-propionyl-CoA was used as sub...

We previously showed that genetic inactivation of malonyl-CoA decarboxylase (MCD), which regulates fatty acid oxidation, protects mice against high-fat diet-induced insulin resistance. Development of insulin resistance has been associated with activation of the inflammatory response. Therefore, we hypothesized that the protective effect of MCD inhibition might be caused by a favorable effect on...

The 2-oxoacid dehydrogenase complexes (ODHc) consist of multiple copies of three enzyme components: E1, a 2-oxoacid decarboxylase; E2, dihydrolipoyl acyl-transferase; and E3, dihydrolipoyl dehydrogenase, that together catalyze the oxidative decarboxylation of 2-oxoacids, in the presence of thiamin diphosphate (ThDP), coenzyme A (CoA), Mg²⁺ and NAD⁺, to generate CO₂, NADH and the corresponding a...

Malonyl-CoA decarboxylase (MCD) catalyzes the degradation of malonyl-CoA, an important modulator of fatty acid oxidation. We hypothesized that increased fatty acid availability would increase the expression and activity of heart and skeletal muscle MCD, thereby promoting fatty acid utilization. The results show that high-fat feeding, fasting, and streptozotocin-induced diabetes all significantl...

Nicolas VOILLEY*, Raphae$ l RODUIT*, Raffaela VICARETTI*, Christophe BONNY†, Ge! rard WAEBER†, Jason R. B. DYCK‡, Gary D. LOPASCHUK‡ and Marc PRENTKI* *Molecular Nutrition Unit, Department of Nutrition, University of Montreal and the CR Centre Hospitalier de l’Universite! de Montre! al and Institut du Cancer, 1560 Sherbrooke Est, Montreal, Quebec H2L 4M1, Canada, †Department of Internal Medicin...

A recombinant E. coli co-expressing ALA synthase (hemA), NADP-dependent malic enzyme (maeB), and dicarboxylic acid transporter (dctA) was reported to synthesize porphyrin derivatives including iron-containing heme. To enhance the synthesis of bacterial heme, five genes of the porphyrin biosynthetic pathway [pantothenate kinase (coaA), ALA dehydratase (hemB), 1-hydroxymethylbilane synthase (hemC...

In our previous studies, AveI was identified as a negative regulator for avermectin biosynthesis in Streptomyces avermitilis NRRL8165, and the aveI-null mutant of NRRL8165 could produce at least 10-fold more avermectin B1a than its wild-type strain. In order to explore the regulatory mechanism by which aveI affects avermectin biosynthesis, in this study, we performed a global comparative gene e...

The cardiac-enriched isoform of acetyl-CoA carboxylase (ACC2) is a key regulator of mitochondrial fatty acid (FA) uptake via carnitine palmitoyltransferase 1 (CPT1). To test the hypothesis that oxidative metabolism is upregulated in hearts from animals lacking ACC2 (employing a transgenic Acc2-mutant mouse), we assessed cardiac function in vivo and determined rates of myocardial substrate oxida...

Protocatechuate 3,4-dioxygenase (EC 1.13.11.3) catalyzes the ring cleavage step in the catabolism of aromatic compounds through the protocatechuate branch of the beta-ketoadipate pathway. A protocatechuate 3,4-dioxygenase was purified from Streptomyces sp. strain 2065 grown in p-hydroxybenzoate, and the N-terminal sequences of the beta- and alpha-subunits were obtained. PCR amplification was us...

The effects of increased concentration of inorganic phosphate on the biosynthesis of tylosin, the level of the intracellular adenylates, the energy charge, and the activities of enzymes involved in the synthesis of tylonolide precursors were studied in Streptomyces fradiae NRRL 2702. No metabolic response was observed when elevated levels of inorganic phosphate were added in idiophase. Increase...