Example sentences for: penicillins

How can you use “penicillins” in a sentence? Here are some example sentences to help you improve your vocabulary:

  • A similar trend was observed in kinetic studies when using penicillins as substrates (Table 4).

  • As with the I164A mutant, the changes in K m and k cat for the penicillins and carbapenems were relatively small, as compared with the values obtained with the cephalosporins (Table 4).

  • There are over 300 distinct β-lactamases known, and these enzymes have been grouped by a number of classification schemes [ 8 9 10 11 12 13 14 15 ] . For example, Bush has developed a scheme, based on the enzymes' molecular properties, that has four distinct β-lactamase groups [ 10 15 ] . One of the more alarming groups are the Bush group 3 enzymes, which are Zn(II) dependent enzymes that hydrolyze nearly all known β-lactam containing antibiotics and for which there are no or very few known clinical inhibitors [ 9 14 16 17 18 19 ] . The metallo-β-lactamases have been further divided by Bush into subgroups based on amino acid sequence identity: the Ba enzymes share a >23% sequence identity, require 2 Zn(II) ions for full activity, prefer penicillins and cephalosporins as substrates, and are represented by metallo-β-lactamase CcrA from Bacteroides fragilis, the Bb enzymes share a 11% sequence identity with the Ba enzymes, require only 1 Zn(II) ion for full activity, prefer carbapenems as substrates, and are represented by the metallo-β-lactamase imiS from Aeromonas sobria, and the Bc enzymes have only 9 conserved residues with the other metallo-β-lactamases, require 2 Zn(II) ions for activity, contain a different metal binding motif than the other metallo-β-lactamases, prefer penicillins as substrates, and are represented by the metallo-β-lactamase L1 from Stenotrophomonas maltophilia [ 9 ] . A similar grouping scheme (B1, B2, and B3) based on structural properties of the metallo-β-lactamases has recently been offered [ 41 ] . The diversity of the group 3 β-lactamases is best exemplified by the enzymes' vastly differing efficacies towards non-clinical inhibitors; these differences predict that one inhibitor may not inhibit all metallo-β-lactamases [ 18 20 21 22 23 24 25 26 27 28 29 ] . To combat this problem, we are characterizing a metallo-β-lactamase from each of the subgroups in an effort to identify a common structural or mechanistic aspect of the enzymes that can be targeted for the generation of an inhibitor.

  • Beta-lactamases have been widely investigated for their role in the metabolism of antibiotics including cephalosporins and penicillins.

  • Generally, the S224A and S224K mutants exhibited small changes in K m and k cat , while the S224D mutant yielded 20- to 40-fold increased values for K m and >10-fold decreases in k cat when using the penicillins as substrates.

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