In metabolic regulation

Ziegler, D.M. (1985). Role of reversible oxidation-reduction of enzyme thiol-disulphides in metabolic regulation. Annu. Rev. Biochem. 54, 305-329. 

A principle in metabolic regulation that allows one to identify the inhibited step within a metabolic pathway as that reaction for which the concentrations of reactants and products rise and fall, respectively, from their steady-state values when an inhibitor is introduced. In the context of the electron transfer chain, the crossover-point refers to that reaction step demarking the transition from more reduced to more oxidized respiratory enzymes. 

Covalent interconversion of enzymes is well established as a fundamental theme in metabolic regulation. The prototypic reversible interconverting systems include the sequence of phosphorylation/dephosphorylation steps in the activation of mammalian glycogen phosphorylase and pyruvate dehydrogenase as well as the nucleotidyla-tion/denucleotidylation using UTP and ATP in the bacterial glutamine synthetase cascade (see Fig. 1.). 

Some enzymes and carriers are synthesized only in response to the presence of the sugar, or of a structurally similar compound these enzymes and carriers are said to be inducible. Contrariwise, enzyme synthesis may be repressed by an increase in the concentration of ATP, or of some other metabolite. Induction and repression of enzymes and carriers provide two important kinds of control in metabolic regulation. 

Intermediate-level review of the importance of PKB and PI-3K in metabolic regulation by insulin. 

The chemistry of ATP, its role in metabolic regulation, and its catabolic and anabolic roles. 

New treatment of metabolic regulation NEW Chapter 15 gives students the most up-to-date picture of how cells maintain biochemical homeostasis by including modern concepts in metabolic regulation. 

Changes of internal pH during developmental events such as fertilization of sea urchin eggs (+0.3 unit) have been recorded. However, the significance of pH changes in metabolic regulation remains uncertain.0... 

Enzymes as Control Elements in Metabolic Regulation Daniel E. Atkinson... 

Inhibition of the initial step of a biosynthetic pathway by an end product of the pathway is a recurrent theme in metabolic regulation. In addition, many key enzymes are regulated by ATP, adenosine diphosphate (ADP), AMP, or inorganic phosphate ion (Pi). The concentrations of these materials provide a cell with an index of whether energy is abundant or in short supply. Because ATP, ADP, AMP, or P often are chemically unrelated to the substrate of the enzyme that must be regulated, they usually bind to an allosteric site rather than to the active site. 

The rate of degradation of an enzyme is reflected in its half-life - the time taken for 50% of the protein to be degraded. Most enzymes that are important in metabolic regulation have short half-lives, and are termed labile enzymes. 

Hochachka, P.W. (1999b). Two research paths for probing the roles of oxygen in metabolic regulation. Brazilian J. Med. Biol. Res. 32 661-672. 

Retinoids (e.g. retinoic acid) are involved in development and in metabolic regulation (e.g. through induction of expression of PEPCK, the rate limiting enzyme in gluconeogenesis). Retinoic acid derives from retinol, which in turn derives from ingestion of plant a-, 3- and "/-carotenes and other carotenes. Retinoic acid acts via retinoic acid receptors and retinoid X receptors note that these receptors can heterodimerize in the nucleus with other related hormone receptors such as PPA-Rs. The developmental importance of retinoic acid is underscored by the teratogenicity of retinoic acid and other vitamin A related compounds, notably some compounds developed for anti-acne properties. 

F. M., Matschinsky. A lesson in metabolic regulation inspired by the glucokmase glucose sensor paradigm. Diabetes, 45, 223 241, 1996. 

D. Ziegler, Role on Reversible Oxidation-Reduction of Enzyme Thiols-Disulfides in Metabolic Regulation, On Rev Biochem 54 (1985) 305-329. 

Nearly all of these chemical transformations are catalyzed en-zymically within the plasmalemma (inside the yeast cell-wall), which is the semipermeable membrane that encloses the protoplasm. Many of these enzymes are present in the cells, even under widely differing conditions of their growth, but a number of processes are involved in enzymic regulation and, thus, in the regulation of sugar catabolism. Some enzymes may be synthesized only in response to the presence of the sugar or of a structurally similar compound. Contrariwise, enzyme synthesis may be repressed by an increase in the concentration of ATP or of some other end-product. These enzyme inductions (for a review, see Ref. 5) and repressions (for a review, see Ref. 6) are two important kinds of control in metabolic regulation. 

E.A. Newsholme and B. Crabtree, Substrate cycles in metabolic regulation and in heat generation, Biochem. Soc. Symp., 1976, 43, 61-109. 

Cydic purine nucleoside monophosphates (cAMP and cGMP) are important second messengers in metabolic regulation (i.e. they carry messages within the cell, triggered by extracellular hormones). 

Selective tools have helped determine possible roles of each ERR family member. ERRa knockout mice show relatively normal anatomical features, but have much lower fat deposits than wild-type mice and are resistant to high-fat diet-induced obesity, suggesting a role for ERRoc in metabolic regulation [39]. The mice also lack the ability to maintain body temperature due to defects in mitochondrial function [39]. ERRp knockout mice die before birth, suggesting an important role for ERRP during embryonic development [40]. The ERRy knockout mice die within 1 week after birth due to faulty oxidative metabolism in the heart [41]. 

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