An additional ionic bond suggested by molecular modelling of TEM-2 might induce a slight discrepancy between catalytic properties of TEM-1 and TEM-2 β-lactamases |
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| Authors: | El Bachir Chaï bi,Sedigheh Farzaneh,Jean Pé duzzi,Michel Barthé lé my,Roger Labia |
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| Affiliation: | Muséum National Histoire Naturelle, CNRS URA 401, 63 rue Buffon, 75231 Paris Cedex 05, France; U MR 175, CNRS-MNHN, 6 rue de l'Université, 29000 Quimper, France |
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| Abstract: | Abstract The plasmid-mediated TEM-1 and TEM-2 β-lactamases are the most commonly encountered among Gram-negative bacteria. They belong to molecular class A, and differ by one amino acid at position 39: TEM-1 have a glutamine and TEM-2 a lysine. Kinetic parameters ( k cat and K m) and catalytic efficiency ( k cat/ K m) of TEM-1 and TEM-2 β-lactamases are slightly, but significantly different. For all antibiotics except methicillin and cefazolin, the catalytic efficiency values of TEM-2 are clearly greater than that of TEM-1. Molecular modelling of TEM-2, when compared to that of TEM-1, showed an additional ionic bond between Lys-39 and Glu-281. |
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| Keywords: | TEM-type β-lactamase Molecular modelling Amino acid substitution |
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