Characterization of pulmonary surfactant protein D: its copurification with lipids.
Surfactant protein D (SP-D) is a collagenous surfactant associated protein synthesized by alveolar type II cells. SP-D was purified from the supernatant of rat bronchoalveolar lavage fluids obtained by centrifugation at 33,000 x gav for 16 h. The contents of SP-D and SP-A in fractions obtained by the centrifugation of rat bronchoalveolar lavage were determined by enzyme-linked immunoassay. The total content of SP-D was approximately 12% of that of SP-A in these lavage fluids. 99.1% of SP-A was present in the 33,000g pellet, whereas 71.1% of SP-D was in the 33,000g supernatant. Analysis by high performance liquid chromatography reveals that lipids are copurified with isolated SP-D. Phosphatidylcholine accounted for 84.8% of the phospholipids copurified with SP-D. Unlike SP-A, SP-D in the purified and delipidated form failed to compete with 125I-labeled SP-A for phosphatidylcholine binding, and to aggregate phospholipid liposomes. The present study demonstrates that lipids are copurified with SP-D, that SP-D and SP-A distribute differently in rat bronchoalveolar lavage fluids, and that SP-D in the purified and delipidated form does not exhibit interaction with lipids in the same fashion as SP-A.
Kuroki
Y
Y
Department of Biochemistry, Sapporo Medical College, Japan.
Shiratori
M
M
Ogasawara
Y
Y
Tsuzuki
A
A
Akino
T
T
D000818:Animals; D001667:Binding, Competitive; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry*; D002498:Centrifugation; D002851:Chromatography, High Pressure Liquid; D004797:Enzyme-Linked Immunosorbent Assay; D006023:Glycoproteins / Q000302:isolation & purification* / Q000378:metabolism; D008297:Male; D010713:Phosphatidylcholines / Q000302:isolation & purification / Q000378:metabolism; D010743:Phospholipids / Q000302:isolation & purification* / Q000378:metabolism; D011510:Proteolipids / Q000302:isolation & purification / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000378:metabolism; D037662:Pulmonary Surfactant-Associated Protein A; D037663:Pulmonary Surfactant-Associated Protein D; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000302:isolation & purification* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D006023:Glycoproteins; D010713:Phosphatidylcholines; D010743:Phospholipids; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037663:Pulmonary Surfactant-Associated Protein D; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants