Lung "surfactant convertase" is a member of the carboxylesterase family.
The extracellular conversion of lung surfactant from tubular myelin to the small vesicular form has previously been shown to require a serine-active enzyme called "surfactant convertase." In the present study, a 72kD serine-active enzyme previously identified in mouse lung alveolar lavage and having convertase activity was partially sequenced. Sixty-eight residues obtained from amino acid sequencing of this protein show that it is a new member of the mouse carboxylesterase family (EC 3.1.1.1). The 72kD lung protein also has esterase activity. A commercial esterase of the same family was able to reproduce surfactant convertase bioactivity in vitro, unlike several serine proteinases previously tested. We conclude that surfactant convertase is a carboxylesterase which mediates a biochemical step in the extracellular metabolism of surfactant.
Krishnasamy
S
S
Department of Molecular and Cellular Biochemistry, Stritch School of Medicine, Loyola University of Chicago, Maywood, Illinois 60153, USA.
Gross
N J
NJ
Teng
A L
AL
Schultz
R M
RM
Dhand
R
R
D000595:Amino Acid Sequence; D000818:Animals; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D007531:Isoflurophate / Q000378:metabolism / Q000494:pharmacology; D008099:Liver / Q000201:enzymology; D008168:Lung / Q000201:enzymology* / Q000378:metabolism; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D011663:Pulmonary Surfactants / Q000378:metabolism*; D017421:Sequence Analysis; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D013552:Swine
D004791:Enzyme Inhibitors; D011663:Pulmonary Surfactants; D007531:Isoflurophate; D002265:Carboxylic Ester Hydrolases; D012697:Serine Endopeptidases; C068328:surfactant subtype convertase