title: Small-angle x-ray and light-scattering study of native and trypsin-modified methionyl-tRNA synthetase from Escherichia coli.
abstract: Small-angle X-ray scattering experiments were performed on an absolute scale on solutions of methionyl-tRNA synthetase from Escherichia coli in its native and trypsin-modified forms. A light-scattering study was performed on the same solutions to verify monodispersity. The structural parameters for the trypsin-modified enzyme, radius of gyration (2.48 nm), volume (90 nm3), surface/volume (1.5 nm-1) and the distribution of chords can account for an equivalent prolate ellipsoid of revolution having an axial ratio 2.3 and a maximum length of 9 nm, with a creviced surface. The rsults obtained for the native enzyme [i.e. radius of gyration (4.3 nm), volume (244 nm3), distribution of the scattering intensity and distribution of chords] exclude the possibility of a very compact quaternary structure and suggest that the enzyme consists of at least two globular parts, probably the two protomers, linked together by interactions involving a limited region of the structure.
mesh_terms: D000604:Amino Acyl-tRNA Synthetases; D004926:Escherichia coli / Q000201:enzymology*; D008027:Light; D008433:Mathematics; D008718:Methionine-tRNA Ligase; D008968:Molecular Conformation; D008970:Molecular Weight; D012542:Scattering, Radiation; D014357:Trypsin; D014961:X-Ray Diffraction
chemical_list: D014357:Trypsin; D000604:Amino Acyl-tRNA Synthetases; D008718:Methionine-tRNA Ligase