Quantitating the statistical distribution of deuterium incorporation to extend the utility of H/D exchange MS data.
Measuring the statistical distribution of deuterium incorporated into enzymatically derived peptide fragments provides a valuable dimension to hydrogen/deuterium exchange mass spectrometry data. In this paper, we will discuss our improvement to the linear least-squares method for determining this distribution, through the addition of "zeroes" to the end of the deuterated isotopic envelope, to partially compensate for data truncation due to finite instrumental signal-to-noise ratios. The value of the distribution is demonstrated in a simple experimental example, where the linearity between average deuteration and percent D2O used to label test peptides hides a more complex relationship between the site-labeling probability and the total number of sites. This method offers the opportunity to resolve cases where a single peptide experiences distinct, independent biochemical states with each bearing a unique average deuteration; this can occur when a protein is modified to substoichiometric levels. From the experimentally determined distribution of a heterogeneously deuterated peptide, it was possible to extract the average deuteration of each component of the mixture.
Chik
John K
JK
Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, Canada.
Vande Graaf
Jaclyn L
JL
Schriemer
David C
DC
D003903:Deuterium / Q000737:chemistry*; D041961:Deuterium Exchange Measurement / Q000379:methods*; D019277:Entropy; D006859:Hydrogen / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D011522:Protons; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D016008:Statistical Distributions
D010446:Peptide Fragments; D011506:Proteins; D011522:Protons; D006859:Hydrogen; D003903:Deuterium