Analysis of variant forms of porcine surfactant polypeptide-C by nano-electrospray mass spectrometry.
Electrospray (ES) mass spectrometry has been used to analyse preparations of porcine pulmonary surfactant polypeptide-C (SP-C). A number of variant forms of the native 35-residue dipalmitoylated peptide were detected including (a) C-terminally methylated SP-C, (b) C-terminally methylated and methionine oxidized SP-C, (c) N-terminally truncated, C-terminally methylated and methionine oxidized SP-c, (d) C-terminally elongated, C-terminally methylated and methionine oxidized SP-C, and (e) tripalmitoylated, C-terminally methylated and methionine oxidized SP-C. C-terminal methylation and methionine oxidation are probably a consequence of the sample handling procedure. The occurrence of the C-terminally elongated form of SP-C has implications for the in vivo processing of proSP-C and the Tandem mass spectrometry (MS/MS) was used to confirm the amino acid sequence of SP-C and the presence of palmitoyl groups covalently linked to the peptide. Some of the structures of the variant forms of SP-C were determined by MS/MS.
Griffiths
W J
WJ
Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
Gustafsson
M
M
Yang
Y
Y
Curstedt
T
T
Sjövall
J
J
Johansson
J
J
D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000032:analysis; D011510:Proteolipids / Q000032:analysis*; D011663:Pulmonary Surfactants / Q000032:analysis*; D013552:Swine
D010446:Peptide Fragments; D011510:Proteolipids; D011663:Pulmonary Surfactants