Synapt g2 si quadrupole time of flight q tof mass spectrometer

Metabolites were detected using a Waters Synapt G2-Si quadrupole time of flight (Q-TOF) mass spectrometer equipped with a MALDI source (Waters, Milford, MA). HDImaging v1.4 and MassLynx v4.2 software, were used for data acquisition. Tissue samples were imaged with a 30 μm step size using a solid state Nd:YAG laser operating at 355 nm (laser energy 175, sampling rate 3 s, and repetition rate of 2500 Hz). Untargeted measurements were performed in resolution MS mode, in the 25–700 m/z range in positive mode. Calibration was performed prior analysis using red phosphorus clusters as a reference standard, and during spectra acquisition using tryptophan (205.0105 m/z) as internal lock mass. The nanoscaping data (Figure S2), obtained from cell extracts, were acquired on a Bruker Microflex MALDI-TOF MS with the MSP Biotarget adapter (Bruker Daltonics, Billerica, MA) at 35% laser power.
Metabolite identification was based on the accurate mass of the molecule matched against the METLIN database, observed isotope pattern and presence of related adducts at consistent spatial distribution. MS/MS experiments were performed to confirm metabolite identities when possible.

To confirm the molecular weight of the purified VIM-2 and VIM-24 MBLs, ESI-MS was performed on a Waters SynaptG2-Si quadrupole time-of-flight (Q-TOF) mass spectrometer equipped with a LockSpray dual electrospray ion source, using glu-1-fibrinopeptide B as the lock mass. The Synapt G2-Si instrument was calibrated with sodium iodide using a m/z 50–2000 mass range. For the experiments described herein, samples were desalted and concentrated using a C18 ZipTip (Millipore, Billerica, MA) according to the manufacturer’s protocol. Eluted protein samples were diluted with 50% acetonitrile and 0.2% formic acid and directly infused at a rate of 50 μL/min, and data were collected for 1 min. Lock mass spectra were collected prior to each sample in a similar manner. The tune settings for each data run were as follows: capillary voltage of 3.2 kV, sampling cone of 30, source offset of 30, source temperature of 100 °C, desolvation temperature of 450 °C, cone gas of 50 L/h, desolvation gas of 600 L/h, and nebulizer bar of 6.0. Spectra were analyzed using MassLynx version 4.1. Spectra were modified for lock mass deviations by applying a gain factor and deconvoluted using MaxEnt1.