Using theoretical protein isotopic distributions to parse small-mass-difference post-translational modifications via mass spectrometry.

ABSTRACT: Small-mass-difference modifications to proteins are obscured in mass spectrometry by the natural abundance of stable isotopes such as (13)C that broaden the isotopic distribution of an intact protein. Using a ZipTip (Millipore, Billerica, MA, USA) to remove salt from proteins in preparation for high-resolution mass spectrometry, the theoretical isotopic distribution intensities calculated from the protein's empirical formula could be fit to experimentally acquired data and used to differentiate between multiple low-mass modifications to proteins. We could readily distinguish copper from zinc bound to a single-metal superoxide dismutase (SOD1) species; copper and zinc only differ by an average mass of 1.8 Da and have overlapping stable isotope patterns. In addition, proteins could be direct

SUBMITTER: Rhoads TW 

PROVIDER: S-EPMC4119010 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature