| Literature DB >> 16406807 |
Kris De Vriendt1, Gonzalez Van Driessche, Bart Devreese, Carine Bebrone, Christine Anne, Jean-Marie Frère, Moreno Galleni, Jozef Van Beeumen.
Abstract
Metallo-beta-lactamases are zinc containing enzymes that are able to hydrolyze and inactivate beta-lactam antibiotics. The subclass B2 enzyme CphA of Aeromonas hydrophila is a unique metallo-beta-lactamase because it degrades only carbapenems efficiently and is only active when it has one zinc ion bound. A zinc titration experiment was used to study the zinc affinity of the wild-type and of several mutant CphA enzymes. It shows that a second Zn(2+) is also bound at high ion concentrations. All samples were analyzed using mass spectrometry in combination with an automated nanoESI source. The metal-free enzyme has a bimodal charge distribution indicative of two conformational states. A completely folded enzyme is detected when the apo-enzyme has bound the first zinc. Intensity ratios of the different enzyme forms were used to deduce the zinc affinities. CphA enzymes mutated in metal ligands show decreased zinc affinity compared to wild-type, especially D120 mutants.Entities:
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Year: 2006 PMID： 16406807 DOI： 10.1016/j.jasms.2005.10.007
Source DB: PubMed Journal: J Am Soc Mass Spectrom ISSN： 1044-0305 Impact factor: 3.109