FIG 2.

Reconstructed spectra, monitoring the reactivation of avibactam-inactivated VCC-1 using ESI-MS. After incubation of VCC-1 with excess avibactam, followed by removal of the inactivator, reactivation of the enzyme was monitored by measuring the amount of covalently labeled VCC-1 at 1 h (top), 10 h (middle), and 32 h (bottom). The peak at 29,190 atomic mass units (amu) corresponds to that of recombinant VCC-1 (expected mass = 29,193 amu), and the peak at 29,455 amu corresponds to that of recombinant VCC-1 covalently modified with 1 molecule of avibactam (expected mass = 29,458 amu). The y axes show ion count.