Figure 5.

Proteolysis of the alanine variant of MinLeu with proteinase K. Products of an early digestion time point, separated by reverse-phase HPLC, are shown. The region of the HPLC chromatogram from 45 to 75 min is expanded, with the full chromatogram shown in the Inset. Initial cuts were identified as those cleavage sites that create two complementary digestion products spanning the entire MinLeu sequence. It possible that complementary fragments are generated from secondary digestion of larger initial fragments. This is unlikely, however, because we have analyzed very early digestion time points in which we do not observe other secondary digestion fragments without a complementary product. The identities of individual species, their predicted masses, and their masses measured by mass spectrometry, are indicated. Amino acid residues are numbered as in the context of full-length α-LA, with the N-terminal methionine designated as residue zero, and the linker residues designated as Link1, -2, and -3.