X-ray small-angle studies of the pyruvate dehydrogenase core complex from Escherichia coli K-12 |
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Authors: | Helmut Durchschlag |
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Institution: | (1) Institut für Physikalische Chemie der UniversitÄt Graz, Austria;(2) Biochemie II, UniversitÄt Regensburg, Germany |
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Abstract: | The pyruvate dehydrogenase core complex from E. coli K-12, defined as the multienzyme complex which can be obtained with a unique polypeptide chain composition, has been investigated in solution with the X-ray small-angle technique. The molecular mass of the core complex of 3.78·106 daltons verifies the ratio of polypeptide chains of 161616 of the three enzyme components, pyruvate dehydrogenase, dihydrolipoamide transacetylase, and dihydrolipoamide dehydrogenase, present in the complex. In connection with the values obtained for the radius of gyration (156.5 å), volume (1.07·107 å3) and amount of solvent associated with the complex (1.03 g/g) a loose packing of subunits in the complex has to be assumed. The maximum diameter of the core complex of 433 å, as determined from the correlation function, corroborates the large extension of the complex. The comparison of experimental and theoretical scattering curves reveals a relatively isometric overall shape of the core complex.Enzymes: Pyruvate dehydrogenase complex = pyruvate dehydrogenase (EC 1.2.4.1) plus dihydrolipoamide transacetylase (EC 2.3.1.12) plus dihydrolipoamide dehydrogenase (EC 1.6.4.3). |
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Keywords: | Correlation Function Radius of Gyration Molecular Weight Volume Isometric Overall Shape |
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