Cycloserine antibacterial activity

The molecular targets for the antibacterial activity of the penicillin and related j8-lactam antibiotics such as the cephalosporins are a group of bacterial enzymes known as penicillin-binding proteins (PBPs). The PBPs are essential to the final stages of bacterial cell wall biosynthesis. Penicillin and other j8-lactam antibiotics inhibit PBPs, thereby inhibiting bacterial cell wall biosynthesis, which eventually results in bacterial cell lysis. (Vancomycin and cycloserine are nonpenicillin antibiotics that also inhibit bacterial cell wall biosynthesis through other mechanisms.)... 

The nucleotide UDP-GNAc-lactyl-L-Ala-D-Glu-L-Lys accumulates in Staph, aureus treated with D-cycloserine. This accumulation is inhibited competitively by D-alanine, but not by its L-isomer. It has thus been suggested that the antibacterial activity of D-cycloserine (XXVIII) depends on its structural similarity to D-alanine, which enables it to inhibit the incorporation of the latter into the muramic acid-peptide of the cell wall. 

Peptide antibiotics include a wide range of compounds such as cycloserine (an amino acid), bacitracin (a cyclic peptide), thiostrepton (a Unear peptide), neocarzinostatin (a polypeptide) and bleomycin (a glycoprotein). These compounds possess either antibacterial and/or antitumor activity and should be regarded as conventional peptides for the purposes of HPLC. For a detailed overview of the HPLC retention times of the more common peptide antibiotics in various buffer systems the reader is referred to a recent review (Aszalos and Aquilar, 1984). The recommended stationary phase is a Vydac RP-18 column because it produced the least amount of peak taiUng. Mobile... 

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