Holocarboxylase synthetase (HCS) catalyzes the covalent attachment of biotin to five biotin-dependent carboxylases in human cells. Multiple carboxylase deficiency (MCD) is a life-threatening disease characterized by the lack of carboxylase activities because of deficiency of HCS activity. Here, we report the obligatory participation of HCS in the biotin-dependent stimulation of the level of HCS...

The reacting enzyme sedimentation procedure has been used to identify the catalytically competent oligomeric forms of pyruvate carboxylases isolated from yeast and from chicken and rat liver. The latter two enzymes have been found to exist in at least two and three active oligomerit species, respectively. At low protein concentrations and with its substrates present, pyruvate carboxylase from c...

The mechanisms of carbon concentration in marine diatoms are controversial. At low CO2 , decreases in O2 evolution after inhibition of phosphoenolpyruvate carboxylases (PEPCs), and increases in PEPC transcript abundances, have been interpreted as evidence for a C4 mechanism in Thalassiosira pseudonana, but the ascertainment of which proteins are responsible for the subsequent decarboxylation an...

OBJECTIVE Biotin is a coenzyme composed of four carboxylases. It presents in amino acid catabolism, fatty acid synthesis, and gluconeogenesis. Biotinidase recycles the vitamin biotin. A biotinidase deficiency is a neurocutaneous disorder with autosomal recessive inheritance. The symptoms can be successfully treated or prevented by administering pharmacological doses of biotin. Although, accordi...

The carboxylation of pyruvate in the absence of acetylCoA by sheep kidney pyruvate carboxylase has been demonstrated and the characteristics of the reaction have been investigated. Under optimal conditions, the maximal specific activity for the reaction was 25 % of that obtained in the presence of saturating concentrations of acetyl-CoA. The reaction was markedly stimulated by K+, NH4+, Rb+, an...

Biotinylation is widely used in DNA, RNA and protein probing assays as this molecule has generally no impact on the biological activity of its substrate. During the streptavidin-based detection of glycoproteins in Lactobacillus rhamnosus GG with biotinylated lectin probes, a strong positive band of approximately 125 kDa was observed, present in different cellular fractions. This potential glyco...

The occurrence, activity and plasticity of the CAM pathway is described from an introductory viewpoint, framed by the use of the four "Phases" of CAM as comparative indicators of the interplay between environmental constraints and internal molecular and biochemical regulation. Having described a number of "rules" which seem to govern the CAM cycle and apply uniformly to most species, a number o...

In vivo CO(2) fixation and in vitro phosphoenolpyruvate (PEP) carboxylase levels have been measured in lupin (Lupinus angustifolius L.) root nodules of various ages. Both activities were greater in nodule tissue than in either primary or secondary root tissue, and increased about 3-fold with the onset of N(2) fixation. PEP carboxylase activity was predominantly located in the bacteroid-containi...

Acetyl-CoA carboxylase catalyzes the first committed step in fatty acid synthesis. In Escherichia coli, the enzyme is composed of three distinct protein components: biotin carboxylase, biotin carboxyl carrier protein, and carboxyltransferase. The biotin carboxylase component has served for many years as a paradigm for mechanistic studies devoted toward understanding more complicated biotin-depe...

The active site of pyruvate carboxylase, like those of all biotin-dependent carboxylases, is believed to consist of two spatially distinct sub-sites with biotin acting as a mobile carboxy-group carrier oscillating between the two sub-sites. Some of the factors that influence the location and rate of movement of the N-carboxybiotin were studied. The rate of carboxylation of the alternative subst...