FTICR mass spectra of protonated holomyoglobin ions produced from ESI of protein solutions (a) without any pretreatment and (b) pretreated with L-ascorbic acid for . The peaks denoted by “∗” in (b) correspond to protonated apomyoglobin ions with .
Time sequences of pulse events in (a) SORI-CID and (b) IRMPD experiments.
SORI-CID mass spectra of at different levels of rf attenuation (in dB). The fragment ions and result from charged heme loss and neutral heme loss, respectively.
Fractions of charged (◻) vs neutral (엯) heme loss of , and their ratios (∎), as a function of SORI excitation energy. The dissociation fraction is defined as , where and are the intensities of precursor ions and fragment ions, respectively.
IRMPD spectra of with (×), 10 (∎), and 11 (엯). The peak intensities represent dissociation fractions as defined in Fig. 4.
IRMPD of pure ferric . (a) Time trace of charged heme loss at each of five laser intensities for the ion only. (b) Plot of the natural logarithm of the first-order unimolecular dissociation rate constant, , vs the natural logarithm of the laser intensity (in units of ). The fitted slopes are , , and at , 11, and 12, respectively. The frequency of the OPO laser excitation was fixed at .
Plot of the natural logarithm of the dissociation rate constants of charged vs neutral heme loss of (∎,◻) and (●,엯) as a function of the natural logarithm of the laser intensity (in units of ). The laser excitation frequency was fixed at . The fitted slope of charged vs neutral heme loss is vs , respectively.
Article metrics loading...
Full text loading...