Labeling of Bifidobacterium longum cells with 13C-substituted leucine for quantitative proteomic analyses.

ABSTRACT

Stable isotope labeling of amino acids in cell culture was used for Bifidobacterium longum. A comprehensive proteomic strategy was developed and validated by designing an appropriate semidefined medium that allows stable replacement of natural leucine by [(13)C6]leucine. Using this strategy, proteins having variations of at least 50% in their expression rates can be quantified with great confidence.