Mass spectrometry has served as a major tool for the discipline of proteomics
to catalogue proteins in an unprecedented scale. With chemical and metabolic techniques
for stable isotope labeling developed over the past decade, it is now routinely used as a
method for relative quantification to provide valuable information on alteration of protein
abundance in a proteome-wide scale. Recently, absolute or stoichiometric quantification
of proteome is becoming feasible, in particular, with the development of strategies with
isotope-labeled standards composed of concatenated peptides. On the other hand,
remarkable progress has been also made in label-free quantification methods based on the
number of identified peptides. Here we review these mass spectrometry-based
approaches for absolute quantification of proteome and discuss their implications.
Keywords: Quantitative proteomics, Mass spectrometry, Absolute quantification,
Stable isotope labeling, Label-free.
