FIGURE 1.

Peptide substrate specificity profile of mouse and human granzyme A. A, following four rounds of selection, 62 (mGzmA) or 79 (hGzmA) phage-displayed nonameric peptides were sequenced, aligned, and analyzed to identify selected residues at each subsite. Shading of bars represents strength of selection as follows: white, <2σ; gray, 2σ to 4σ; black, >4σ. B, reaction rates were determined for mGzmA and hGzmA cleaving both of the optimized peptide substrates Abz-GLFRSLSS(K-dnp)D (white bars) and Abz-VANRSAS(K-dnp)D (gray bars). Data shown are the means ± S.D. of three independent replicates. *, p < 0.05; **, p < 0.01; n.s., p > 0.05 in Student's t test.