title: Spin-label study of the mobility of enzyme-bound lipoic acid in the pyruvate dehydrogenase multienzyme complex of Escherichia coli.
abstract: The lipoic acid residues covalently bound to the transacetylase component of the pyruvate dehydrogenase multienzyme complex of Escherichia coli were selectively modified by reaction with 4-maleimido-2,2,6,6-tetramethylpiperidino-oxyl. The electron-spin-resonance spectrum of the spin-labelled enzyme indicates that the bound nitroxide groups have high mobilities relative to the protein molecule. This physicochemical evidence is consistent with the view that the dithiolane ring of a lipoyl residue is capable of rapid migration between the active sites of the component enzymes in the catalytic mechanism.
mesh_terms: D004926:Escherichia coli / Q000201:enzymology*; D008301:Maleimides; D011768:Pyruvate Dehydrogenase Complex / Q000032:analysis*; D013113:Spin Labels; D008063:Thioctic Acid / Q000032:analysis*
chemical_list: D008301:Maleimides; D011768:Pyruvate Dehydrogenase Complex; D013113:Spin Labels; D008063:Thioctic Acid