81755-86-4Relevant articles and documents
Hydrolysis of 6-Alkyl Penicillins catalysed by β-Lactamase I from Bacillus cereus and by Hydroxide Ion
Buckwell, Stephen C.,Page, Michael I.,Longridge, Jethro L.
, p. 1809 - 1814 (2007/10/02)
Second-order rate constants for the hydroxide ion-catalysed hydrolysis of 6-alkyl penicillins are independent of the length of the alkyl side-chain and replacement of the amido by an amino group decreases the susceptibility to nucleophilic attack on 6-aminopenicillanic acid only three-fold.B. cereus β-lactamase I catalyses the hydrolysis of 6-alkyl penicillins with values of kcat/Km which are at least 50-fold greater than that shown by 6-aminopenicillanic acid.For the enzyme-catalysed reaction kcat/Km increases with increasing chain length, reaching a maximum with hexylpenicillin, and then decreases.The binding energy of the alkyl group is weak, only 1.45 kJ mol-1 per methylene residue.Although there appears to be a recognition site for the amido group there is no specific pocket in β-lactamase I for the recognition of hydrophobic residues in the 6-acylamido side-chain of penicillins.
