Bacillus cereus metallo-b-lactamase uses a branched mechanism to hydrolyse different antibiotics

TIONI, M.F.; LLARRULL, L.I.; VILA, A.J.

Ann Arbor, Michigan

Conferencia; 12th International Conference on Biological Inorganic Chemistry; 2005

The mechanism of hydrolysis of different beta-lactam antibiotics by the metallo-beta-lactamase BcII from Bacillus cereus was studied by stopped-flow/photodiode array detector. The changes in the metal coordination of the enzyme substituted with different Co(II)/enzyme ratios were evaluated during the reaction, which allowed us to conclude that BcII uses a branched mechanism for beta-lactam hydrolysis. Although the reaction was slower with lower Co(II)/enzyme ratios, the spectroscopic signature of the intermediates involved were identical for the enzyme substituted with one or two metal equivalents, This suggests that the catalytic species involved in the reaction could be the same whether the enzyme is in its mono- or di-metallated forms.