Hydrolysis of 6-alkyl penicillins catalysed by β-lactamase I from Bacillus cereus and by hydroxide ion

The effect of the carboxy group on the chemical and β-lactamase reactivity of β-lactam antibiotics

“…208-209 "C (lit.,4 210 "C); G(C2H6]DMSO) Kinetics.-The kinetics of the enzyme-catalysed reactions were analysed as previously described. 6 The kinetics of the alkaline hydrolysis were studied in aqueous solution by monitoring the change in U.V. absorption.…”

“…This is the typical ratio shown by nearly all penicillins (1). 6 The ratio is less for cephalosporins and for the phenylacetamido derivative (2) (R = PhCH, and X = OAc) it is 7 x lo4, despite the similar chemical reactivity of cephalosporins and penicillins (Table ).…”

The Relative Catalytic Efficiency of β-Lactamase Catalyzed Acyl and Phosphyl Transfer

“…An unresolved mixture of the pure diastereoisomers (1:1 ratio) was obtained in 30% yield (300 mg), after separation by column chromatography on silica 60 gel. HPLC (220 nm Ethyl N-(benzyloxycarbonyl)amidomethylphosphonyl anthranilate (methyl ester) (7). This compound was synthesised from methyl anthranilate (0.56 ml) and the phosphonyl chloride (obtained from 1g of the monoester (3)) as described previously.…”

“…␤-Lactamase activity was determined against benzylpenicillin by a spectrophotometric method (7). Concentrations of the Ent.…”

The mechanism of catalysis and the inhibition of β-lactamases

“…24 The two experimental kinetic parameters associated with simple systems exhibiting Michaelis-Menten behaviour are the second-order rate constant k cat /K m determined below saturation and the first order rate constant k cat determined above saturation. 25 The interpretation of these experimental macroscopic rate constants as they vary with parameters such as pH, substituents in the substrate 26,27 and amino acid replacement in the enzyme 28 depends upon the model assumed for the reaction pathway. The overall reaction pathway for the serine b-lactamases is given in eqn.…”