Regulatory Behavior of Monomeric Enzymes

Jc, Meunier; Buc, Jean; Navarro, Alfonso; Ricard, Jacques

doi:10.1111/j.1432-1033.1974.tb03826.x

Cited by 88 publications

(13 citation statements)

References 29 publications

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“…Ricard, Meunier and Buc first formulated the mnemonic model in an effort to explain the ability of monomeric enzymes to display non-hyperbolic kinetics [16, 25]. Their model expanded on earlier conceptual work by Rabin and Frieden who postulated that the conformation of an enzyme following product release could be different from the initial enzyme state [9, 22].…”

Section: Mechanisms Of Monomeric Kinetic Cooperativitymentioning

confidence: 99%

Cooperativity in monomeric enzymes with single ligand-binding sites

Porter

Miller

2012

Bioorganic Chemistry

100

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Cooperativity is widespread in biology. It empowers a variety of regulatory mechanisms and impacts both the kinetic and thermodynamic properties of macromolecular systems. Traditionally, cooperativity is viewed as requiring the participation of multiple, spatially distinct binding sites that communicate via ligand-induced structural rearrangements; however, cooperativity requires neither multiple ligand binding events nor multimeric assemblies. An underappreciated manifestation of cooperativity has been observed in the non-Michaelis-Menten kinetic response of certain monomeric enzymes that possess only a single ligand-binding site. In this review, we present an overview of kinetic cooperativity in monomeric enzymes. We discuss the primary mechanisms postulated to give rise to monomeric cooperativity and highlight modern experimental methods that could offer new insights into the nature of this phenomenon. We conclude with an updated list of single subunit enzymes that are suspected of displaying cooperativity, and a discussion of the biological significance of this unique kinetic response.

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Section: Mechanisms Of Monomeric Kinetic Cooperativitymentioning

confidence: 99%

Cooperativity in monomeric enzymes with single ligand-binding sites

Porter

Miller

2012

Bioorganic Chemistry

100

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“…The view developed above, that the regulatory power of a monomeric enzyme is antagonistic to its efficiency receives support from several concrete experimental facts. For instance, monomeric wheatgerm hexokinase LI, which exhibits interesting regulatory properties (Meunier et al, 1974), is a poor catalyst when compared with other phosphotransferases. Similarly, yeast hexokinase in its dissociated monomeric form and its optimum pH (8.5) is a very 1978 efficient enzyme and does not exhibit any atypical behaviour (Colowick, 1973).…”

Section: Discussionmentioning

confidence: 99%

Generalized microscopic reversibility, kinetic co-operativity of enzymes and evolution

Ricard¹

1978

Biochemical Journal

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Generalized microscopic reversibility implies that the apparent rate of any catalytic process in a complex mechanism is paralleled by substrate desorption in such a way that this ratio is held constant within the reaction mechanism [Whitehead (1976) Biochem. J. 159, 449--456]. The physical and evolutionary significances of this concept, for both polymeric and monomeric enzymes, are discussed. For polymeric enzymes, generalized microscopic reversibility of necessity occurs if, within the same reaction sequence, the substrate stabilizes one type of conformation of the active site only. Generalized microscopic reversibility suppresses the kinetic co-operativity of the slow transition model [Ainslie, Shill & Neet (1972) J. Biol. Chem. 247, 7088--7096]. This situation is obtained if the free-energy difference between the corresponding transition states of the two enzyme forms is held constant along the reaction co-ordinate. This situation implies that the 'extra costs' of energy (required to pass each energy barrier) that are not covered by the corresponding binding energies of the transition states vary in a similar way along the two reaction co-ordinates. The regulatory behaviour of monomeric enzymes is discussed in the light of the concept of 'catalytic perfection' proposed by Albery & Knowles [(1976) Biochemistry 15, 5631--5640]. These authors claim that an enzyme will be catalytically 'perfect' when its catalytic efficiency is maximum. If this situation occurs for a monomeric enzyme obeying either the slow transition or the mnemonical model, it can be shown that the kinetic co-operativity disappears. In other words, kinetic co-operativity of a monomeric enzyme is 'paid for' at the expense of catalytic efficiency, and the monomeric enzyme cannot be simultaneously co-operative and catalytically very efficient. This is precisely what has been found experimentally in a number of cases.

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“…. Thus, it has been known for a long time [125][126][127][128][129][130][131][132][133] that some enzymes retain, or recall, the conformation stabilized by the last product of the reaction sequence for a while before relapsing to the initial conformation. Under steady-state conditions, the coexistence of two free enzyme forms generates a kinetic cooperativity even for one-sited monomeric enzymes.…”

Section: Review Articlementioning

confidence: 99%

Enzymes and the supramolecular organization of the living cell. Information transfer within supramolecular edifices and imprinting effects

Ricard

Gontero

Avilán

et al. 1998

Cellular and Molecular Life Sciences (CMLS)

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Simple considerations of statistical mechanics phate dehydrogenase complex from Chlamydomonas show that the association of an enzyme with another protein or with an 'inert' surface results in a decrease of chloroplasts. Whereas the isolated oxidized phosphoribulokinase is almost completely inactive, it becomes its information content and thus that it receives an active when bound to glyceraldehyde phosphate dehy-'instruction' from this protein or from the surface. As a consequence, the free energy stored in the enzyme in-drogenase. Moreover, upon dissociation of the comcreases, and this energy may be used to alter the intrin-plex, the phosphoribulokinase retains for a while an sic catalytic properties of the enzyme. This may imply, imprinting exerted by glyceraldehyde phosphate dehyfor instance, that an enzyme which is devoid of activity drogenase. It then displays properties that are may have its activity enhanced when bound to another markedly different from those of the free stable enzyme. Thermodynamics allows us to calculate the protein or to a membrane. A possible consequence of this communication between proteins is that, upon dis-amount of energy stored in this enzyme and used to sociation of the complex, one of these enzymes may facilitate substrate binding and catalysis. There is thus little doubt that information and instructions are transtransitorily retain an imprinting of the other protein and this imprinting may in turn alter the properties of ferred from protein to protein within enzyme comthe enzyme. Different enzyme systems may illustrate plexes that result in a complete change of their biological function. this view. A particular emphasis has been put on the

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Regulatory Behavior of Monomeric Enzymes

Cited by 88 publications

References 29 publications

Cooperativity in monomeric enzymes with single ligand-binding sites

Cooperativity in monomeric enzymes with single ligand-binding sites

Generalized microscopic reversibility, kinetic co-operativity of enzymes and evolution

Enzymes and the supramolecular organization of the living cell. Information transfer within supramolecular edifices and imprinting effects

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