The presence of a Met residue at the junction of the prosegment and mature peptide in proHNP1 sequence (see Fig. 1 ) offered a non-enzymatic approach to generate HNP1 from proHNP1 utilizing cyanogen bromide (CNBr) cleavage [28] . Cleavage of proHNP1A with CNBr, followed by C18 RP-HPLC, gave rise to a major peptide product (Fig. 3A ) with a mass (Fig. 3B ) and HPLC retention time (Fig. 3C ) matching that of natural HNP1. However, CNBr digestion of proHNP1B generated multiple species (Fig. 3A ) that had masses consistent with oxidized HNP1 (Fig. 3B ), but which eluted later than native HNP1 in RP-HPLC (Fig. 3C) . On AU PAGE, HNP1 derived from proHNP1A comigrated with natural HNP1. However, HNP1 derived from proHNP1B migrated more rapidly than the natural standard (Fig. 3D) . These data demonstrate that proHNP1A contained folded HNP1 with native disulfide linkages but the mature peptide in proHNP1B, although oxidized, is misfolded and contains non-native disulfide linkages. In solution, HNP1 exists as a non-covalent dimer [37] and the dimeric form corresponds to the single band observed in AU PAGE (Selsted et al., unpublished data) . Therefore, it is likely that the higher mobility of proHNP1B-derived HNP1 (Fig. 3D ) is due to the monomeric state of this conformer.