Four of the 5 biotin-dependent carboxylases (BDC) are in the mitochondria. BDC replace intermediates in the Krebs [tricarboxylic acid (TCA)] cycle that are regularly removed for the synthesis of key metabolites such as heme or amino acids. Heme, unlike amino acids, is not recycled to regenerate these intermediates, is not utilized from the diet, and must be synthesized in situ. We studied wheth...

Biotin functions as a coenzyme for four carboxylases involved in energy metabolism in mammals. Besides these classical functions, biotin has novel functions in the cellular processes via the modulation of gene expression. In this study, we examined the alteration of gene expression by biotin administration in the liver of streptozotocin (STZ)-induced diabetic rats. In comparison with the contro...

Biotin-dependent carboxylases are widely distributed in nature and have important functions in many cellular processes. These enzymes share a conserved biotin carboxylase (BC) component, which catalyzes the ATP-dependent carboxylation of biotin using bicarbonate as the donor. Despite the availability of a large amount of biochemical and structural information on BC, the molecular basis for its ...

The catalytic r81e of thiaminoproteins in intermediary carbohydrate metabolism has long been recognized. Although numerous theories have been advanced to explain the chemical mechanism by which the diphosphothiamine (DPT) moiety of thiaminoproteins contributes to the catalytic properties of these enzymes, the modus operandi of DPT has remained unsolved. Perhaps the main reason for this has been...

Urea carboxylase (UC) is conserved in many bacteria, algae, and fungi and catalyzes the conversion of urea to allophanate, an essential step in the utilization of urea as a nitrogen source in these organisms. UC belongs to the biotin-dependent carboxylase superfamily and shares the biotin carboxylase (BC) and biotin carboxyl carrier protein (BCCP) domains with these other enzymes, but its carbo...

Acetyl-CoA carboxylases ACC1 and ACC2 catalyze the carboxylation of acetyl-CoA to malonyl-CoA, regulating fatty-acid synthesis and oxidation, and are potential targets for treatment of metabolic syndrome. Expression of ACC1 in rodent lipogenic tissues and ACC2 in rodent oxidative tissues, coupled with the predicted localization of ACC2 to the mitochondrial membrane, have suggested separate func...

Amino acids composing a flexible loop (loop 6) of the eight-stranded barrel domain of the L-subunit of Synechococcus ribulose bisphosphate carboxylase/oxygenase (EC 4.1.1.39) involved in reaction intermediate stabilization have been modified by site-specific mutagenesis. Changes at positions both distant and within the active site affect overall catalysis and substrate partitioning. Most signif...

Progressive multiple sclerosis (MS) is a severely disabling neurological condition, and an effective treatment is urgently needed. Recently, high-dose biotin has emerged as a promising therapy for affected individuals. Initial clinical data have shown that daily doses of biotin of up to 300 mg can improve objective measures of MS-related disability. In this article, we review the biology of bio...

Malonyl-CoA, generated by acetyl-CoA carboxylases ACC1 and ACC2, is a key metabolite in the control of fatty acid synthesis and oxidation in response to dietary changes. ACC2 is associated to the mitochondria, and Acc2-/- mice have a normal lifespan and higher fatty acid oxidation rate and accumulate less fat. Mutant mice fed high-fat/high-carbohydrate diets weighed less than their WT cohorts, ...

The two carboxylation reactions performed by phosphoenolpyruvate carboxylase (PEPC) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) are vital in the fixation of inorganic carbon for C4 plants. The abundance of PEPC is substantially elevated in C4 leaves, while the location of Rubisco is restricted to one of two chloroplast types. These differences compared with C3 leaves have been...