MALDI-TOF MS Characterization of Anti-JFL21

Anti-JFL21 was further subjected to MALDI-TOF MS analysis and the methanol solvent was used as a negative control. The experiments were conducted using an ultrafleXtreme^TM MALDI-TOF MS instrument (Bruker Daltonics, Germany) equipped with a 337 nm pulsed nitrogen laser. All tested samples (2 μL) were mixed with an equal volume of the matrix (a saturated solution of α-cyano-4-hydroxycinnamic acid in 50% acetonitrile with 0.1% TFA), as described previously (Kim et al., 2010 (link); Piewngam et al., 2018 (link)). The sample was spotted onto the gold-coated plate and air-dried. Then the target plate was loaded into an ultrafleXtreme^TM MALDI-TOF MS instrument (Bruker Daltonics, Germany). The mass spectrum was analyzed in the range of 500–3500 Da. MALDI-TOF MS/MS coupled with LIFT mode in the same spectrometer was used to analyze the fragment ions of the selected precursor ions for further characterization of the amino acid sequence. Other identification score criteria used were those recommended by the manufacturer.