Purification and biochemical characterization of equine pulmonary surfactant protein D.
OBJECTIVE
To characterize surfactant protein D (SP-D) isolated from bronchoalveolar lavage fluid (BALF) of healthy horses.


METHODS
BALF from 10 Thoroughbreds (5 males, 5 females; 26 to 40 months old) without history or clinical signs of respiratory tract disease.


METHODS
BALF was obtained and centrifuged at 33,000 X g. The supernatant was applied to a mannose-Sepharose 6B affinity column in the presence of calcium, and the bound protein fraction was analyzed by use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoblot analysis; amino acid composition was determined and partial sequencing was done. Phospholipid binding and liposome aggregation assay were performed, using purified proteins.


RESULTS
The protein isolated by use of mannose affinity matrices was SP-D. It bound carbohydrates and phosphatidylinositol, which are the characteristic features of SP-D isolated from other animal species. Amino acid analysis and partial primary sequence of the isolated protein indicated high homology with rat and human SP-D. Furthermore, immunoblot analysis indicated that equine SP-D reacted with human and rat SP-D-specific antibodies.


CONCLUSIONS
SP-D exists in equine lungs; its measurement may be useful in evaluating equine lung disease.
Hobo
S
S
Clinical Science and Pathobiology Division, Equine Research Institute, Japan Racing Association, Tochigi.
Ogasawara
Y
Y
Kuroki
Y
Y
Akino
T
T
Yoshihara
T
T
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel / Q000662:veterinary; D005260:Female; D006023:Glycoproteins / Q000737:chemistry / Q000302:isolation & purification*; D006736:Horses; D006801:Humans; D015151:Immunoblotting / Q000662:veterinary; D008081:Liposomes; D008297:Male; D010743:Phospholipids / Q000378:metabolism; D037663:Pulmonary Surfactant-Associated Protein D; D011663:Pulmonary Surfactants / Q000737:chemistry / Q000302:isolation & purification*; D051381:Rats
D000596:Amino Acids; D006023:Glycoproteins; D008081:Liposomes; D010743:Phospholipids; D037663:Pulmonary Surfactant-Associated Protein D; D011663:Pulmonary Surfactants