Combined fractional diagonal chromatography results. (A) Distribution of the 498 proteins identified by COFRADIC with respect to the 3 different approaches. (B) Exemplary scheme of N-terminal COFRADIC. Upon blockage of free amines (i) and tryptic digest (ii), fractions are collected during a first-dimension high-performance liquid chromatography run (iii). Due to subsequent blockage by TNBS, internal peptides are shifted during a second high-performance liquid chromatography run (iv), whereas true N-terminal peptides are eluted in the same timeframe as before (iii). (C) COFRADIC results are mostly covered as well by identifications based on shotgun approaches. (D) List of selected N-termini elucidated by N-terminal COFRADIC from platelet membrane proteins. N-termini often differ from literature (Swiss-Prot database) or are newly assigned.