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 beta-lactamases.
The plasmid-mediated TEM-1 and TEM-2 beta-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 (kcat and Km) and catalytic efficiency (kcat/Km) of TEM-1 and TEM-2 beta-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.
Chaïbi
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EB
Muséum National Histoire Naturelle, CNRS URA 401, Paris, France.
Farzaneh
S
S
Péduzzi
J
J
Barthélémy
M
M
Labia
R
R
D002384:Catalysis; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D006090:Gram-Negative Bacteria / Q000201:enzymology / Q000235:genetics; D007700:Kinetics; D008958:Models, Molecular; D015394:Molecular Structure; D011487:Protein Conformation; D001618:beta-Lactamases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D001618:beta-Lactamases; C034413:beta-lactamase TEM-1; C056342:beta-lactamase TEM-2