title: NMR studies of the hydrogen bonds involving the catalytic triad of Escherichia coli thioesterase/protease I.
abstract: Escherichia coli thioesterase/protease I (TEP-I) is a lipolytic enzyme of the serine protease superfamily with Ser(10), Asp(154) and His(157) as the catalytic triad residues. Based on comparison of the low-field (1)H nuclear magnetic resonance spectra of two mutants (S10G and S12G) and two transition state analogue complexes we have assigned the exchangeable proton resonances at 16.3 ppm, 14.3 ppm, and 12.8 ppm at pH 3.5 to His(157)-N(delta1)H, Ser(10)-O(gamma)H and His(157)-N(epsilon2)H, respectively. Thus, the presence of a strong Asp(154)-His(157) hydrogen bond in free TEP-I was observed. However, Ser(10)-O(gamma)H was shown to form a H-bond with a residue other than His(157)-N(epsilon2).
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei 11529, Taiwan ROC.
authors.forename: Sergiy I
authors.initials: SI
authors.lastname: Tyukhtenko
authors.forename: Alexandra V
authors.initials: AV
authors.lastname: Litvinchuk
authors.forename: Chi-Fon
authors.initials: CF
authors.lastname: Chang
authors.forename: Ruey-Jyh
authors.initials: RJ
authors.lastname: Leu
authors.forename: Jei-Fu
authors.initials: JF
authors.lastname: Shaw
authors.forename: Tai-Huang
authors.initials: TH
authors.lastname: Huang
mesh_terms: D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D008245:Lysophospholipase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D033903:Periplasmic Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017354:Point Mutation; D011522:Protons; D012694:Serine / Q000737:chemistry
chemical_list: D029968:Escherichia coli Proteins; D033903:Periplasmic Proteins; D011522:Protons; D012694:Serine; D008245:Lysophospholipase; C400724:tesA protein, E coli