Catalytically active filaments – pyruvate decarboxylase fromNeurospora crassa. pH-controlled oligomer structure and catalytic function


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Abstract

Pyruvate decarboxylase is a key enzyme in organisms whose energy metabolism is based on alcoholic fermentation. The enzyme catalyses the nonoxidative decarboxylation of 2-oxo acids in the presence of the cofactors thiamine diphosphate and magnesium ions. Pyruvate decarboxylase species from yeasts and plant seeds studied to date are allosterically activated by their substrate pyruvate. However, detailed kinetic studies on the enzyme from Neurospora crassa demonstrate for the first time the lack of substrate activation for a yeast pyruvate decarboxylase species. The quaternary structure of this enzyme species is also peculiar because it forms filamentous structures. The complex enzyme structure was analysed using a number of methods, including small-angle X-ray solution scattering, transmission electron microscopy, analytical ultracentrifugation and size-exclusion chromatography. These measurements were complemented by detailed kinetic studies in dependence on the pH.Structured digital abstractPDC and PDC bind by light scattering (View Interaction: 1, 2)PDC and PDC bind by cosedimentation in solution (View Interaction: 1, 2)PDC and PDC bind by electron microscopy (View interaction)Pyruvate decarboxylase species from yeasts and plant seeds studied so far are allosterically activated by their substrate pyruvate. However, detailed kinetic studies on the enzyme from Neurospora crassa demonstrate for the first time the lack of substrate activation for a yeast pyruvate decarboxylase species. The quaternary structure of this enzyme species is also peculiar as it forms filamentous structures.

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