Mono- and binuclear Zn-beta-lactamase from Bacteroides fragilis: catalytic and structural roles of the zinc ions.
The Bacteroides fragilis Zn-beta-lactamase is active with a mono- and a binuclear zinc site. The apoenzyme produced by removal of both Zn ions does not recover full activity upon readdition of Zn2+ in contrast to an active mono-Zn form prepared at pH 6.0. Differences in k(cat) values observed are substrate-dependent implying distinct mechanisms for the mono- and binuclear species. The substrate profile of a Zn,Cd hybrid obtained by selective exchange of one zinc ion is different from that of the Zn2 enzyme with a remarkable 15-fold increased activity with cefoxitin as substrate.
Paul-Soto
R
R
Fachrichtung 12.4 Biochemie, Universität des Saarlandes, Saarbrücken, Germany.
Hernandez-Valladares
M
M
Galleni
M
M
Bauer
R
R
Zeppezauer
M
M
Frère
J M
JM
Adolph
H W
HW
D000900:Anti-Bacterial Agents / Q000378:metabolism; D001051:Apoenzymes / Q000378:metabolism; D001441:Bacteroides fragilis / Q000201:enzymology*; D001665:Binding Sites; D002104:Cadmium / Q000378:metabolism / Q000494:pharmacology; D002152:Calorimetry, Differential Scanning; D002614:Chelating Agents / Q000494:pharmacology; D003067:Coenzymes / Q000737:chemistry / Q000494:pharmacology; D003956:Dialysis; D004229:Dithiothreitol / Q000494:pharmacology; D007700:Kinetics; D010848:Picolinic Acids / Q000494:pharmacology; D011489:Protein Denaturation; D013050:Spectrometry, Fluorescence; D013379:Substrate Specificity; D013816:Thermodynamics; D017186:Titrimetry; D015032:Zinc / Q000737:chemistry / Q000378:metabolism*; D001618:beta-Lactamases / Q000378:metabolism*; D047090:beta-Lactams
D000900:Anti-Bacterial Agents; D001051:Apoenzymes; D002614:Chelating Agents; D003067:Coenzymes; D010848:Picolinic Acids; D047090:beta-Lactams; D002104:Cadmium; D001618:beta-Lactamases; D015032:Zinc; D004229:Dithiothreitol; C004860:dipicolinic acid