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Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)
 

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Val-237 for Ala substitution in the TEM-2 beta-lactamase dramatically alters the catalytic efficiencies towards carbenicillin and ticarcillin.

The mutant 554 of TEM-2 beta-lactamase was selected for a decrease in the resistance to carbenicillin of an Escherichia coli K12 carrier. The amino acid sequence of the mutant beta-lactamase was determined by manual Edman degradation analysis of proteolytic peptides. A single substitution Val for Ala was localized at position 237. The mutant exhibited only 2% of the catalytic efficiency of the wild-type enzyme towards carbenicillin and ticarcillin, whereas it retained 30-60% of the hydrolytic activity towards other penicillin and cephalosporin substrates. Carfecillin, the phenyl ester of the side-chain carboxyl group of carbenicillin, was hydrolysed as a good substrate. This suggests that the behaviour of the mutant enzyme towards carbenicillin may result from ionic rather than steric constraints. A molecular model of the Val-237 TEM-2 mutant suggests possible electrostatic interaction between Glu-171 and the carboxylic group of the side chain of carbenicillin.[1]

References

  1. Val-237 for Ala substitution in the TEM-2 beta-lactamase dramatically alters the catalytic efficiencies towards carbenicillin and ticarcillin. Barthélémy, M., Péduzzi, J., Rowlands, D., Paul, G., Moreau, G., Labia, R. FEMS Microbiol. Lett. (1994) [Pubmed]
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