Article Figures & Data
Figures
- FIG. 1.
(A) Domain structure of the cloned LambdaSa1 and LambdaSa2 lysins; (B) structure of the GBS peptidoglycan showing the glycosidic bond cleaved by LambdaSa2 lysin and the endopeptidase cleavage site for both lysins.
- FIG. 2.
Negative ion mass spectra of the low-molecular-weight products of lysin-digested bacterial cell walls. (A) LambdaSa2-digested GBS cell walls; (B) LambdaSa2-digested GBS cell walls treated with 5% (vol/vol) aqueous triethylamine; (C) LambdaSa1 plus mutanolysin-digested GBS cell walls; (D) LambdaSa2-digested Staphylococcus aureus cell walls; (E) LambdaSa2-digested Streptococcus pneumoniae cell walls. The 694.4 m/z fragment is due to a disaccharide dipeptide composed of N-acetylglucosamine, N-acetylmuramic acid, alanine, and glutamine. The 652.4 m/z fragment has one less acetyl group, and the 736.4 m/z fragment has one more acetyl group than the core glycopeptide (694.4).
- FIG. 3.
Possible structures of a disaccharide containing N-acetylglucosamine and N-acetylmuramic acid linked to Ala-Gln.
- FIG. 4.
Identification of the site of glycosidic bond cleavage by GLC-mass spectrometry. (A) Total ion chromatogram (TIC) of a mixture of derivatized N-acetylglucosamine, N-acetylglucosaminitol, N-acetylmuramic acid, and N-acetylmuramitol; (B to E) selected ion chromatograms of the same sample for m/z 584 (GlcNAC-ol) (B), m/z 552 (GlcNAc) (C), m/z 626 (MurNAc-ol) (D), and m/z 462 (MurNAc) (E) ions; (F) selected ion chromatogram for the four ions of m/z 462, 552, 584, and 626 for a LambdaSa2 digest of GBS cell walls; (G) selected ion chromatogram for the same four ions as those used for panel F for a double digest of GBS cell walls by LambdaSa1 and mutanolysin. SIM, selected ion monitoring.
