P-Lactamase activity

Pratt, R. F. Functional evolution of the serine P-lactamase active site. J. Chem. Soc. Perkin Trans. 2 2002, 851-861. 

Highly populated protein domain families of H. pylori include (1) the cellular component Helicobacter outer membrane protein family (2) the sell family, which is associated with P-lactamase activity (3) members of the CagA and VacA protein families, which are secreted into host cells and are involved in pathogenesis (4) the ABC transporter family, which is associated with ATP-dependent transport of molecules across the membrane (5) the DNA methyltransferase protein domain family (6) the radical SAM (S-adenosylmethionine) family associated with various metabolic functions of pathogens and (7) the response regulator receiver domain family, which is involved in receiving the signal from the sensor domain in bacterial two-component systems. 

E. Third-generation cephalosporins are susceptible to p-lactamase activity. 

Correct choice = E. Unlike the penicillins, cephalosporins are less sensitive to p-lactamase activity. Inflammation does increase penetration of penicillin into the CSF. All penicillin derivatives, including penicillin V, can potentially trigger an allergic reaction in patients sensitive to penicillin G. Cefoxitin can often be used in these patients. However, caution should be exercised, since there is about 5 to 15% crossreactivity. 

Tazobactam (Fig. 10.6F) is a penicillanic acid sulphone derivative marketed as a combination with piperacillin. Alone it has poor intrinsic antibacterial activity but is comparable to clavulanic acid in inhibiting P-lactamase activity. 

The virus titer diminished from 10 to 10 (PFU/ml) during the first four hours without further reduction. The titer of T2, a more hydrophilic virus, decreased only one order of magnitude and the recovery of p-lactamase activity was 70%. Computer simulation results demonstrating the effects of various process variables are also presented. 

Inactivation of phage T2 in p-lactamase solution by QAC-treated beads is shown in Figure 4. The initial T2 titer was 3.0 x 10 PFU/ml. A quantity of 0.8 g of beads were mixed with 10 ml of p-lactamase solution. Fifteen percent of the viruses survived this treatment. The amount of total protein in the solution was 80% of the initial value after the adsorption process, while the recovery of p-lactamase activity was at least 70%. It was the purpose of this experiment to demonstrate that QAC-treated beads can effectively remove viruses from a protein solution without significantly losing the activity of the protein. Optimal adsorption condition and mode of operation ought to be determined by studying the interactive effects of pH, ionic strength, and temperature of the solution, with the specific t)qjes of virus and protein of interest. 

Sykes, R. B. and Nordstrom, K. "Microiodometric determination of p-lactamase activity" Antimicrob. Agents Chemotheraphy. 1972. 1 94-99. 

Figure 2.7. Demonstration of a p-lactamase reporter cell line. In a final volume of 0.02 mL, 5000-10,000 cells were seeded overnight at 37°C before being stimulated with excess agonist or antagonist for 4 h. The resultant p-lactamase activity was measured after a 1-h incubation with CCF2 (Aurora Biosciences) at the indicated wavelengths in an LJL Analyst fluorometer. (a) The unstimulated cells, (b) the cells incubated with agonist, and (c) cells treated with agonist and excess antagonist.

P-Lactamase activity Activity towards new substrate 32000-fold greater resistance to cefotaxime DNA shuffling + selection E. coli [37]... 

Nedra Kanmaratne, D., Farmer, S. and Hancock, R. E. W. (1993) Synthesis of bulky P-lactams for inhibition of cell surface p-lactamase activity. Bioconjugate Chem. 4 434-439. 

SAR of Cefuroxime. The presenee of a 5y -alkoxiamino substituent in the drug molecule is closely associated with the prevalent P-lactamase activity in these eephalosporins. Perhaps its inclusion into the second generation cephalosporins is duly justified due to the faetthat its antibacterial spectrum bears a close similarity to that of cefamandole (see Seetion 3.2.1.2.1). 

ALKALINE D-STEREOSPECIFIC ENDOPEPTIDASE WITH P-LACTAMASE ACTIVITY FROM BACILLUS CEREUS [25]... 

Phe, D-Phe and D-Phe ierf-butyl ester. The enzyme was not active toward L-Phe methyl ester, (L-Phe)2 methyl ester, (L-Phe)4, Boc-(L-Phe)4, Boc-(L-Phe)4 methyl ester, (D-VaDa, (D-Leu)2, or (D-Ala)n (n = 2 - 5). These properties indicated that the enzyme is an endopeptidase that acts D-stereospecifically upon peptides composed of aromatic D-amino acids. On the other hand, a dimer was formed when D-Phe methyl ester and D-Phe amide were the substrates. Eight stereoisomers of Phe trimer were synthesized, and their effectiveness as substrates for the enzyme was tested. The enzyme recognized the configuration of the second D-Phe of tripeptides and catalyzed the hydrolysis of the second peptide bond from the N-terminus. The calculated Vmax/Km values for the peptides containing L-Phe were lower than that for (D-Phels, affected by the configuration of the neighboring L-Phe. The enzyme also showed P-lactamase activity toward ampicillin and penicillin G. The calculated Vmax values of the enzyme for b-lactam compounds were about the same as those for (D-Phe)3 and (D-Phe)4, while the Km values were several hundred times larger. On the other hand, carboxypeptidase DD and D-aminopeptidase activities were undetectable. 

The extensive use of penicillins and other P-lactam antibiotics in medicine over the last forty years has given rise to an increasing number of resistant bacteria. This bacterial resistance is mainly due to the production of P-lactamases [8], which efficiently catalyse the hydrolysis of the P-lactam ring. Like D,D-peptidases, most of the P-lactamases are serine proteases operating via the same mechanism as the transpeptidases. However, for P-lactamase activity k3 must be much larger than k2/K (Scheme 2). Recently, a structural homology between the two classes of bacterial enzymes has been established, suggesting that P-lactamases are evolutionary descendants of the D,D-peptidases [9,10]. 

More recently, Cocuzza [61] prepared iV-acetyl-deazathienamycin 96 [62] following a similar strategy (Scheme 31). The hydroxyethyl side-chain was introduced via the reaction of the zirconium enolate of 93 with acetaldehyde. A 1 1 mixture of threo-trans and erythro-trans isomers 94 was obtained. Compound 96 is devoid of antibacterial activity. However the benzhydryl esters, 97 and 98, are active against gram-positive bacteria and show some anti-P-lactamase activity [61]. 

Thus epoxides 308a or 308b, bearing an acetyl residue and a P-hydroxy-a,p-dimethyl substituent in the trans relationship, have been synthesised in five steps from 306a or 306b (Scheme 93). None of the stereoisomers shows antibacterial activity or D,D-peptidases inhibition. The isomer 308b exhibits weak anti-P-lactamase activity at 1 mM concentration B. cereus). 

For routine detection of P-lactamase activity, a fresh bacterial culture is mixed with a p-lactam solution (meropenem or ertapenem) (Hrabak et al. 2011 Burckhardt and Zimmermarm 2011 Hrabak et al. 2013, 2014 Studentova et al. 2015) (Fig. 12.2). After incubation at 35-37 °C for 2 h, the reaction mixture is centrifuged and the supernatant is apphed onto a MALDI target, covered by a matrix solution (HCCA or DHB), and measured in a positive ion mode. In the first descrip-... 

Direct detection of p-lactamase activity has been established as a routine method in mai microbiological diagnostic laboratories (Hrabak et al. 2014). Especially in the case of a direct detection of caibapenemase activity, the MALDI-TOF MS hydrolysis assay should soon be accepted as a gold standard method and may serve as a reference technique together with spectrophotometric assays. The main advantage of MS tools is the ability to detect rapidly both antibiotic hydrolytic products and intact lactamases. 

Another approach used in the search for novel p-lactams has involved screening techniques designed to detect inhibitors of p-lactamase activity. Clavulanic acid and the olivanic acids were first detected in p-lactamase inhibitor screens (Brown et al., 1977 Butterworth et al., 1979). 

Xing, B. Khanamiryan, A. Rao, J. Cell-permeable near-infrared fluorogenic substrates for imaging P-lactamase activity. J. Am. Chem. Soc. 2005, 127, 4158 159. 

Shao, Q. Zheng, Y Dong, X. Tang, K. Yan, X. Xing, B. A covalent reporter of p-lactamase activity for fluorescent imaging and rapid Screening of antibiotic-resistant bacteria. Chem. Eur. J. 2013, 19,10903-10910. 

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