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. Author manuscript; available in PMC: 2014 May 22.
Published in final edited form as: Biochemistry. 2009 Jun 2;48(21):4557–4566. doi: 10.1021/bi9003292

FIGURE 2.

FIGURE 2

Deconvoluted ESI-MS spectra of (A) SHV-1 and (B) SHV Asn276Asp before and after 15 min inactivation with clavulanate at a inhibitor/enzyme ratio of 1000:1. All measurements have an error of ± 3 Da. Eight distinct mass shifts were identified with both enzymes inactivated with clavulanate. This includes adducts postulated to represent: Δ + 51, terminally inactivated cross-linked or propynoyl enzyme species; Δ + 70, aldehyde; Δ + 88, hydrated aldehyde; Δ + 158, decarboxylated imine; and Δ + 198, acyl-enzyme, imine, cis- or trans-enamine (see Supporting Information, Figure 2 for structures of proposed reaction intermediates) (13, 35).