Figure 4.

Alignment of Fab PL-2 sequences determined by X-ray crystallography (CR) and mass spectrometry (MS). Highlighted in yellow are amino acids whose identities were ambiguous in electron density maps. Highlighted in green are amino acids whose order was ambiguous in mass spectrometry data due to an absence of fragmentation. Highlighted in red are amino acids that were incorrect or absent from the sequence determined by X-ray crystallography but were corrected after mass spectrometry.