Fig. 3.

Mature and pro-SP-B peptides from trachéal aspirates under nonreducing and reducing conditions. Immunoblots of trachéal aspirates from 3 infants without (CON 1, 2, 3) and with (RDS 1, 2, 3) respiratory distress syndrome and purified hSP-B performed under nonreducing and reducing conditions (10% β-mercaptoethanol). Locations of common mature and pro-SP-B peptides (M_r 42, 40, 24, and 21 kDa) and reduced, mature SP-B (8 kDa) are indicated. Trachéal aspirates contain multiple mature and pro-SP-B peptides that do not resolve to an 8-kDa peptide under reducing conditions.