87492-68-0Relevant academic research and scientific papers
Penicillinase-based amperometric biosensor for penicillin G
Gon?alves, Luís Moreira,Callera, Welder F.A.,Sotomayor, Maria D.P.T.,Bueno, Paulo R.
, p. 131 - 133 (2014)
A biosensor for penicillin G was created by immobilizing penicillinase to a gold electrode by means of a cysteine self-assembled monolayer. The biosensor amperometrically monitored the catalytic hydrolysis of penicillin in a very sensible manner. Furthermore, it was successfully used to measure the Michaelis-Menten enzymatic constant and a low limit of detection of 4.5 nM was obtained.
Epimerization of benzylpenicilloic acid in alkaline media
Ghebre Sellassie,Hem,Knevel
, p. 125 - 128 (1984)
5R,6R-Benzylpenicilloic acid was found to epimerize slowly in alkaline media to 5S,6R-benzylpenicilloic acid until equilibrium was established. Epimerization proceeded via the imine tautomer of penamaldic acid rather than the enamine form and was found to favor the 5S,6R-epimer at equilibrium. The conversion process was monitored using both reverse-phase high-performance liquid chromatography and NMR spectroscopy.
Determination of β-lactamase residues in milk using matrix-assisted laser desorption/lonization fourier transform mass spectrometry
Xu, Zhe,Wang, Hao-Yang,Huang, Shi-Xin,Wei, Yuan-Long,Yao, Sheng-Jun,Guo, Yin-Long
, p. 2113 - 2118 (2010)
A selective, fast, and effective enzyme assay based on matrix-assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI-FTMS) for quantifying β-lactamase, an illegal additive in milk products, has been reported. The strengths of the mass spectrometric assay are its response to all substrate and products, simple and direct detection of the conversion of substrate, and facile determination of enzyme activity. Also, MALDI MS is tolerant to many buffer salts and reagents without the requirement of complicated sample pretreatment procedures. In this study, the approach was used to detect the presence of β-lactamases (BLA) in milk samples. The amount of BLA that could be determined in a milk sample is 6 x 10-3 U·mL-1 by this approach. To test the strategy, it has been applied to the fortified milk (adding a BLA product known as an antimicrobial destroyer). It is then tested whether the pasteurization procedure of the milk process affects the activity of BIA in milk samples. This study offers a perspective into the utility of MALJDI-FTMS as an alternative detection tool for BIA screening in milk.
Antibiotic resistance: Mono- and dinuclear zinc complexes as metallo-β-lactamase mimics
Tamilselvi,Nethaji, Munirathinam,Mugesh
, p. 7797 - 7806 (2007/10/03)
Biomimetic systems containing one or two zinc(II) ions supported by phenolate ligands were developed as functional mimics of metallo-β- lactamase. These complexes were shown to catalytically hydrolyze β-lactam- substrates, such as oxacillin and penicillin G. The dinuclear zinc complex 1, which has a coordinated water molecule, exhibits high β-lactamase activity, whereas the dinuclear zinc complex 2, which has no water molecules, but labile chloride ligands, shows a much lower activity. The high β-lactamase ac tivity of complex 1 can be ascribed to the presence of a zinc-bound water molecule that is activated by being hydrogen bonded to acetate substituents. The kinetics of the hydrolysis of oxacillin by complex 1 and the effect of pH on the reaction rates are reported in detail. In addition, the kinetic parameters obtained for the synthetic ana logues are compared with those of the natural metallo-β-lactamase from Bacillus cereus (Bell). To understand the role of the second metal ion in hydrolysis, the syntheses and catalytic activities of two mononuclear complexes (3 and 4) that include coordinated water molecules are described. Interestingly, the mononuclear zinc complexes 3 and 4 also exhibit high activity, supporting the assumption that the second zinc ion is not crucial for the β-lactamase activity.
Role of zinc(II) in β-lactamase II: A model study with a zinc(II)-macrocyclic tetraamine (1,4,7,10-tetraazacyclododecane, cyclen) complex
Koike, Tohru,Takamura, Masahiro,Kimura, Eiichi
, p. 8443 - 8449 (2007/10/02)
Cleavage of the β-lactam ring of benzylpenicillin (1) by a zinc(II) complex of the macrocyclic tetraamine 1,4,7,10-tetraazacyclododecane (cyclen) (8) has been studied in aqueous solution as a functional model of a zinccontaining hydrolytic enzyme, β-lactamase II. β-Lactam hydrolysis by 8 yielding (5R)-benzylpenicilloate (9) is a second-order reaction (the second-order rate constant k is (4.1 ± 0.1) X 10-2M-1 s-1 at 25 °C and I = 0.10 (NaNO3)), and a plot of the hydrolysis rate vs pH (6.6-9.6) gives a sigmoidal curve with an inflection point at pH 7.9, which is identical to the pKa value for the ZnII-bound water of ZnII-cyclen-OH2 (8a). Thus, ZnII-cyclen-OH- (8b) must play a crucial role in the hydrolysis of the β-lactam. The activation energy Ea for the hydrolysis by 8b was determined to be 49 kJ mol-1, lower than the value of 61 kJ mol-1 by aqueous OH-ion. The lower Ea value for 8b is due to the acidic nature of ZnII that stabilizes the anionic tetrahedral intermediate 15. The hydrolysis is subject to anion inhibition by deprotonated succinimide-, SCN-, CH3COO-, or Cl- in the same order as their binding affinity for 8a. The ZnII-cyclen 8 simultaneously catalyzes the isomerization of (5R)-benzylpenicilloate (9) to the 5S-epimer 10 at pH 6.5-9.5. The pH dependency of the catalytic activity discloses that the reactive species is 8a and the kinetically obtained pKa value of 8.0 is almost the same as that obtained thermodynamically. The second-order rate constant kep with 8a is 2.5 ± 0.1 M-1 s-1 at 25 °C and I = 0.10 (NaNO3). Presumably the reaction involves C-S bond rupture due to coordination of ZnII-cyclen, followed by recombination to form 10. While the reaction mechanism of β-lactamase II is still not known in detail, analogies may be drawn with the common role of the ZnII-OH- species in other zinc enzymes such as carbonic anhydrase.
The Mechanisms of Hydrolysis of the γ-Lactam Isatin and its Derivatives
Casey, Lorraine A.,Galt, Ron,Page, Michael I.
, p. 23 - 28 (2007/10/02)
The pH dependences of the rates of hydrolysis of isatin, its N-carboxymethyl derivative and its 5-nitro substituted analogues exhibit a complex behaviour, showing a first- and second-order dependence upon hydroxide ion concentration, as well as a pH-independent pathway.The pH dependence is interpreted in terms of the formation of tetrahedral intermediates in different protonic states which may break down to products via hydroxide ion, hydronium ion and water catalysed pathways.These γ-lactams are as reactive, or more reactive, than benzylpenicillin.
An Esterase with β-Lactamase Activity
Jones, Mark,Page, Michael I.
, p. 316 - 317 (2007/10/02)
Porcine liver esterase selectively catalyses the hydrolysis of the β-lactam of the methyl ester of benzylpenicillin with a kcat/Km of 675 dm3 mol-1 s-1 and without hydrolysing the methyl ester function.
Alcohol-catalysed Hydrolysis of Benzylpenicillin
Davis, Andrew M.,Proctor, Philip,Page, Michael I.
, p. 1213 - 1217 (2007/10/02)
The hydrolysis of benzylpenicillin is catalysed by alkoxide ions and other oxygen bases.Catalysis occurs by a nucleophilic pathway and the intermediate ester can be detected in some cases.The Broensted βnuc for alkoxide ions is 0.97, and is compatible with rate-limiting ring opening of the β-lactam.A solvent isotope effect of 3.2 for the trifluoroethanol-catalysed reaction suggests protonation by water occurs to the departing β-lactam nitrogen.Penicillin in not a particularly effective acylating agent of alcohols.
Thiazolidine Ring Opening in Penicillin Derivatives. Part 2. Enamine Formation
Davis, Andrew M.,Layland, Nicola J.,Page, Michael I.,Martin, Frances,O'Ferrall, Rory More
, p. 1225 - 1229 (2007/10/02)
The alkaline hydrolysis of (3S,5R,6R)-methyl benzylpenicilloate, and the corresponding carboxamide and N-ethylamide, is accompanied by an absorbance increase at 285 nm.This is attributed to a competing elimination reaction across C6-C5 to open the thiazolidine ring and reversibly generate an enamine intermediate.Kinetic analysis and hydrolysis in D2O do not indicate a significant buildup of this intermediate during hydrolysis of the methyl ester.However, over the pH range 4-11 the rate of thiazolidine ring opening is competitive with hydrolysis of the ester function.The deuterium solvent kinetic isotope effect on the ring closure reaction is 7.5.
Thiazolidine Ring Opening in Penicillin Derivatives. Part 1. Imine Formation
Davis, Andrew M.,Jones, Mark,Page, Michael I.
, p. 1219 - 1223 (2007/10/02)
The rate of epimerisation of (3S,5R,6R)-benzylpenicilloic acid at C-5 shows three distinct dependencies upon pH in aqueous solution.Below pH 6 the rate shows a sigmoidal dependence upon pH, whereas it is pH-independent between pH 6 and 12, and above pH 12 the rate is hydroxide-ion dependent.These different regions of pH dependence are interpreted in terms of three mechanistic pathways all of which involve opening the thiazolidine ring by C-S bond fission and re-closure to generate the epimer.At low pH the reaction occurs by unimolecular ring opening of the S-conjugate acid which is kinetically equivalent to the N-conjugate acid of pKa 5.14.The pH-independent pathway involves formation of a zwitterion by unimolecular opening of the neutral thiazolidine.At high pH the unprotonated imine intermediate is formed by concerted hydroxide-ion-catalysed ring opening.The mono- and di-methyl esters of benzylpenicilloate also epimerise at C-5.At low pH the rates are similar for all three compounds but above pH 6 the mono- and di-esters are, respectively, 21 and 1700 times less reactive than the dianion of the diacid.
