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. Author manuscript; available in PMC: 2009 Oct 29.
Published in final edited form as: Mol Microbiol. 2008 Nov 11;71(2):404–420. doi: 10.1111/j.1365-2958.2008.06533.x

Fig. 3. CapD catalyzes amide bond formation between γ-D-glutamyl peptides and the cell wall crossbridge. Assay mix containing 200 μM Abz-γ-D-Glu10-Dnp and 20 μM CapD was incubated in absence or presence of 1 mM wall peptide (L-Ala-D-iGlu-m-DAP) at 22°C for two hours and reaction products were separated by rpHPLC and analyzed by MALDI-TOF MS.

Fig. 3

A. Chromatogram of substrate Abz-γ-D-Glu10-Dnp.

B. Chromatogram of reaction products after incubation of substrate Abz-γ-D-Glu10-Dnp with CapD.

C. Chromatogram of reaction products after incubation of substrates Abz-γ-D-Glu10-Dnp and L-Ala-D-iGlu-m-DAP with CapD. MALDI-TOF analysis of reaction products is provided in Supplemental Tables 1 and 2.

D. Comparison of product yields, expressed as relative abundance (%), for CapD catalysis in panels B and c.

E. Tandem mass spectrometry experiment in the positive reflector mode of m/z 897.35, the CapD transpeptidation product L-Ala-D-iGlu-(Abz-[γ-D-Glu]3)-m-DAP. Daughter ion signals and structural predictions are listed in Table 2.

F. Structural schematic and corresponding b- and y-ions derived from m/z 897.35.