Pyruvate decarboxylase III

Gounaris, Anne D.; Turkenkopf, I. J.; Civerchia, Linda L.; Greenlie, J.

doi:10.1016/0005-2795(75)90114-2

Cited by 42 publications

(15 citation statements)

References 26 publications

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“…This indicates that under the conditions used the formation of apo-PDC is accompanied by a change in quaternary structure. The reduction of the forward scattering corresponds to the dissociation of the holoenzyme in two dimeric halves as previously inferred [3]. The distance between the centres of the dimers in the tetramer calculated from the radii of gyration using the parallel axis theorem is 3.7 nm in agreement with previous observations [16].…”

Section: Dissociation Of Holo-pdc Into Apoenzyme and Recombination Ofsupporting

confidence: 91%

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An X‐ray solution scattering study of the cofactor and activator induced structural changes in yeast pyruvate decarboxylase (PDC)

et al. 1990

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Structure and activation pattern of pyruvate decarboxylase (PDC) from yeast was studied by synchrotron radiation X-ray solution scattering. The results give a direct proof that the reversible deactivation of PDC at pH 8.0 is accompanied by the dissociation of the tetrameric holoenzyme into dimeric halves. The kinetics of this process was followed. At pH 6.5 the dimeric halves reassociate to a tetramer even in the absence of cofactors. The changes of the scattering pattern upon binding of the substrate-like activator pyruvamide indicate that the structure expands in the course of the enzyme activation.Pyruvate decarboxylase; X-ray solution scattering

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Section: Dissociation Of Holo-pdc Into Apoenzyme and Recombination Ofsupporting

confidence: 91%

“…At pH-values above 7.0 the cofactors are released and an apoenzyme is formed. Previous studies [3] suggested that simultaneously the tetrameric enzyme dissociates in two dimeric halves. Recombination of the apoenzyme into the holoenzyme takes place at pH values below 7.0 in the presence of TPP and Mg 2+.…”

Section: Introductionmentioning

confidence: 95%

An X‐ray solution scattering study of the cofactor and activator induced structural changes in yeast pyruvate decarboxylase (PDC)

et al. 1990

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“…The enzyme incubated at alkaline pH for about 30 min and thereafter chromatographed on Sephadex G-50 had lost all its cofactors, and the molecular weight was half that of the holo-enzyme [4,5,10]. When the pH is increased, the first step of the protein denaturation process appears therefore to be subunit dissociation with concomitant loss of the cofactors and, above pH 9, general alkali-induced denaturation sets in.…”

Section: Effects O F P H On the Pyruvate Decarboxylase Diclzroismmentioning

confidence: 99%

“…Since they do not appear in one kinetic phase, a conformational change of the doubly deprotonated holo-enzyme is proposed. A conformational change was also taken into consideration during the study of recombination experiments of the apo-enzyme with a variety of coenzyme analogs [5,13]. If a conformational change is invoked to explain the results of these experiments, it must also be present in the enzyme dissociation process because of the principle of microscopic reversibility.…”

Section: (4)mentioning

confidence: 99%

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Hydroxyl‐Ion‐Induced Subunit Dissociation of Yeast Cytoplasmic Pyruvate Decarboxylase

Hopmann

1980

European Journal of Biochemistry

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Cytoplasmic pyruvate decarboxylase (EC 4.1.1.1, from Saccharomyces curfshevgensis) exhibits in its circular dichroic spectrum in the 250 -320-nm range a multiple two-signal band. This couplet disappears on increasing the pH up to pH 8.5. Two classes of two protons each can be quantified by these spectral changes. The first class dissociates rapidly and the apparent pK is 7.84. The thermodynamic data are AG = 87.7 kJ mol-', AH = + 56.0 kJ mol-', AS = -108 J mol-' K-', very characteristic for the deprotonation of an amino-acid side chain. The second class of the protons hasthefollowingthermodynamicdata: AG = 88.3 kJmol-', A H = -64.3 kJmol-', AS = -5205 mol-' K-' which, in conjunction with kinetic reasoning and in view of enzyme stoichiometry and symmetry, suggests a conformational equilibrium exposing the second two protons. The enzyme dissociates into two dimeric subunits. This dissociation step is considered to be rate-determining for the overall process. The data are: k, = 1.4. lop3, AH' = + 128.3 kJ mol-', AS' = + 136 J mol-' K-' . If there is a conformational equilibrium, the rate constant of product formation k , will be modified by a factor p = Kc/(l + K,) (0 < p 5 1) where Kc is the conformational equilibrium constant. The subunit dissociation appears to be controlled by the enthalpy of activation indicating that a number of interactions, i.e. ionic, hydrogen and hydrophobic bridges, are to be broken. Optimal conditions for the preparation of the apo-enzyme are derived from the data.Pyruvate decarboxylase (2-0x0-acid carboxy-lyase) is a thiamin-pyrophosphate-dependant enzyme and, in view of its function, is advantageously isolated from the cytoplasm of brewers yeast (Sucrharomyces curlshergensis) [l]. Most of our knowledge of the chemical basis of its catalytic mechanism originates from studies of its activity in reconstitution experiments with a variety of chemicaIIy modified coenzyme analogs [2]. These experiments require the preparation of the apo-enzyme [3], which is easily achieved by dissolving the enzyme in alkaline buffer and leaving it for a while at room temperature. Under these conditions, the enzyme decomposes into two subunits with the concomitant release of the coenzyme molecules and the magnesium ions. The enzyme must be composed of two subunits of two monomers each, according to ultracentrifugation [4] and gel chromatographic [5] results.

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Pyruvate Metabolism inSaccharomyces cerevisiae

Pronk

Steensma

Dijken

1996

Yeast

701

456

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In yeasts, pyruvate is located at a major junction of assimilatory and dissimilatory reactions as well as at the branch-point between respiratory dissimilation of sugars and alcoholic fermentation. This review deals with the enzymology, physiological function and regulation of three key reactions occurring at the pyruvate branch-point in the yeast Saccharomyces cerevisiae: (i) the direct oxidative decarboxylation of pyruvate to acetyl-CoA, catalysed by the pyruvate dehydrogenase complex, (ii) decarboxylation of pyruvate to acetaldehyde, catalysed by pyruvate decarboxylase, and (iii) the anaplerotic carboxylation of pyruvate to oxaloacetate, catalysed by pyruvate carboxylase. Special attention is devoted to physiological studies on S. cerevisiue strains in which structural genes encoding these key enzymes have been inactivated by gene disruption.

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Pyruvate decarboxylase III

Cited by 42 publications

References 26 publications

An X‐ray solution scattering study of the cofactor and activator induced structural changes in yeast pyruvate decarboxylase (PDC)

An X‐ray solution scattering study of the cofactor and activator induced structural changes in yeast pyruvate decarboxylase (PDC)

Hydroxyl‐Ion‐Induced Subunit Dissociation of Yeast Cytoplasmic Pyruvate Decarboxylase

Pyruvate Metabolism inSaccharomyces cerevisiae

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