The Specificity Requirements of Bacteriophage T4 Lysozyme

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Abstract
A series of bacterial cell wall glycopeptides of low molecular weight and cell wall nucleotide precursors have been tested for their inhibitory action on the digestion by T4 lysozyme of a radioactively labeled linear uncrosslinked peptidoglycan. The disaccharide‐peptides GlcNAc‐MurNAc‐l‐Ala‐d‐Glu(A2pm) (C5) and GlcNAc‐MurNAc‐l‐Ala‐d‐Glu(A2pm‐d‐Ala) (C6) as well as the monosaccharide‐peptide MurNAc‐l‐Ala‐d‐Glu(A2pm) were found to be good competitive inhibitors (with similar K1 values) whereas the disaccharide‐pentapeptide GIcNAcMurNAc‐l‐Ala‐d Glu‐Gly l‐Lys‐d‐Ala was a poor inhibitor. T4 lysozyme did not catalyse transglycosylation reactions from Escherichia coli B peptidoglycan to the disaccharide‐peptide C6. No changes were seen in the circular dichroism spectra (200–250 nm) or fluorescence emission spectra upon binding of the good inhibitors. The results obtained indicate that T4 lysozyme has a small active site capable of recognizing a unit consisting of MurNAc‐l‐Ala‐d‐Glu(A2pm).