NCBI National Center for Biotechnology Information 
1BBL: THREEDIMENSIONAL SOLUTION STRUCTURE OF THE E3BINDING DOMAIN OF THE DIHYDROLIPOAMIDE SUCCINYLTRANSFERASE CORE FROM THE 2OXOGLUTARATE DEHYDROGENASE MULTIENZYME COMPLEX OF ESCHERICHIA COLIBiochemistry (1992) 31 p.34633471
Abstract The threedimensional solution structure of a 51residue synthetic peptide comprising the dihydrolipoamide dehydrogenase (E3)binding domain of the dihydrolipoamide succinyltransferase (E2) core of the 2oxoglutarate dehydrogenase multienzyme complex of Escherichia coli has been determined by nuclear magnetic resonance spectroscopy and hybrid distance geometrydynamical simulated annealing calculations. The structure is based on 630 approximate interproton distance and 101 torsion angle (phi, psi, chi 1) restraints. A total of 56 simulated annealing structures were calculated, and the atomic rms distribution about the mean coordinate positions for residues 1248 of the synthetic peptide is 1.24 A for the backbone atoms, 1.68 A for all atoms, and 1.33 A for all atoms excluding the six side chains which are disordered at chi 1 and the seven which are disordered at chi 2; when the irregular partially disordered loop from residues 31 to 39 is excluded, the rms distribution drops to 0.77 A for the backbone atoms, 1.55 A for all atoms, and 0.89 A for ordered side chains. Although proton resonance assignments for the Nterminal 11 residues and the Cterminal 3 residues were obtained, these two segments of the polypeptide are disordered in solution as evidenced by the absence of nonsequential nuclear Overhauser effects. The solution structure of the E3binding domain consists of two parallel helices (residues 1423 and 4048), a short extended strand (2426), a fiveresidue helicallike turn, and an irregular (and more disordered) loop (residues 3139). This report presents the first structure of an E3binding domain from a 2oxo acid dehydrogenase complex.(ABSTRACT TRUNCATED AT 250 WORDS)
