Tandem mass spectra of 2 peptides from sheep hemoglobin β-subunit identified in a nymph of an Amblyomma americanum tick. A) Singly protonated AAVTGFWGK. B) Doubly protonated VKVDEVGAEALGR. The peaks are labeled in the conventional manner: b ions include the N-terminus of the peptide and y ions include the C-terminus, with subscripts indicating the number of amino acid residues in the fragment.