The proteins were identified by the peptide-mass fingerprinting method using Mascot Search on the Web (Matrix Science, Ltd, London, UK).
The search for matched protein was later done by using peptide mass fingerprinting (PMF) method in which peptides' masses attained from MALDI were incorporated as the fingerprint in Mascot database.
By combining one-dimensional gel electrophoresis with matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) and peptide mass fingerprinting (see Methods), a total of 809 endosperm proteins were identified.
Interestingly, although pan-monocytes preparations contained a small proportion of CD16+ monocytes, our mass spectrometry fingerprinting method identified unambiguously biomarkers from the most abundant cell population.
The masses and peptide mass fingerprint of the peptides are presented in Table 2.
MALDI peptide mass fingerprint analysis was done on a Reflex IV mass spectrometer (Bruker Daltonics,Germany).
The analyses of the PSD datasets were done either by peptide mass fingerprint or peptide fragmentation fingerprint analysis with Mascot.
Proteins were identified by peptide mass fingerprint and by N-terminal sequencing.
Peptide mass fingerprint (PMF) was acquired between 800 3500 Da.
A mass inaccuracy of ≤100 ppm was allowed for the peptide mass fingerprint.
