Figure 2.

Space-filled model of RNase A with amino acid residues color coded by their solvent accessibility, as determined from targeted amino acid labeling in solution. Color coding: charged amino acid residues (Asp, Glu, Lys, Arg, His) with high solvent accessibility (green) and moderate solvent accessibility (blue), tyrosine residues with high solvent accessibility (orange) and low solvent accessibility (black). Nontargeted amino acid residues are color coded in light gray. Figure illustrated using UCSF Chimera. The arrows point out the location of the three key amino acid residues that provide the catalytic function of the enzyme (H12, K41, H119).