Fig. 1.
Purification and molecular weight analysis of His-hGRP781-508. a Escherichia coli culture was induced with 0.5 mM IPTG at 37 °C for 3 h, the supernatant of cell lysate containing His-hGRP781-508 was collected by centrifugation and subjected to nickel-affinity chromatography. His-hGRP781-508 was eluted with different imidazole concentration of 5, 20, 40, 100, and 150 mM. Aliquots of each fraction were analyzed by 12% (w/v) SDS-PAGE. M molecular weight marker; SF soluble fraction; FT Flow-through. b Mass determination of His-hGRP781-508 was performed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) operating in the electrospray ionization mode. The data were acquired over the mass-to-charge ratio (m/z) range of 43,000–71,000 under normal scan resolution (x axis), the relative intensity (arbitrary units) is shown on the y axis. The data from each spectra were summed and deconvoluted