tailieunhanh - Báo cáo khoa học: Structure and potential C-terminal dimerization of a recombinant mutant of surfactant-associated protein C in chloroform/methanol

The solution structure of a recombinant mutant [rSP-C (FFI)] of the human surfactant-associatedprotein C (hSP-C) in a mixture of chloroform andmethanol was determined by high-resolution NMR spectroscopy. rSP-C (FFI) contains a helix from Phe5 to theC-terminal Leu34 andis thus longer by two residues than the helix of porcine SP-C (pSP-C), which is reportedto start at Val7 in the same solvent. Two sets of resonances at the C-terminus of the peptide were observed, which are explained by low-order oligomerization, probably dimerization of rSP-C (FFI) in its a-helical form. . | Eur. J. Biochem. 271 2076-2085 2004 FEBS 2004 doi Structure and potential C-terminal dimerization of a recombinant mutant of surfactant-associated protein C in chloroform methanol Burkhard Luv1. Alexander Diener2 Rolf-Peter Hummel3 Ernst Sturm3 Wolf-Rudiaer Ulrich4 and Christian Griesinger5 1Institut fur Organische Chemie und Biochemie Technische Universitdt MUnchen Garching Germany 2Institut fur Organische Chemie Johann Wolfgang Goethe-Universitat Frankfurt Germany 3 Department of Physical Organic Chemistry and 4Department of Chemical Research Altana Pharma AG Konstanz Germany 5Max Planck Institut fur Biophysikalische Chemie Gottingen Germany The solution structure of a recombinant mutant rSP-C FFI of the human surfactant-associated protein c hSP-C in a mixture of chloroform and mctaimol was determined by high-resolution NMR spectroscopy. rSP-C FFI contains a helix from Phe5 to the C-terminal Leu34 and is thus longer by two reikluet thmi the helix of porcine SP-C pSP-C which is reported to tsarrt at Val7 in the same solvent. Two sets of resonances at the C-terminus of the peptide were observed which are explained by low-order oligomerization probably dimerization of rSP-C FFI in its a-helical form. The dimerization may be induced by hydrogen bonding of the C-terminal carboxylic groups or by the strictly conservedC-terminal heptapeptide segment with a motif similar to the GxxxG dimerization motif of glycophorin A. Dimerization at the heptapeptide segment would lee p onsistdnt with I mdings stired rn elpptl ospray ionization MS data chemical cross-linking studies and CNBr cleavage data. Keywords dimerization NMR spectroscopy surfactant surfactant protein C SP-C . Surfactant-associated ei m c SP-C ÍS a 34 55-amino-acidpeptied which is highly conservedamong species Table 1 . It is part of the protein-phospholipid pornplex that is secreted ioto the oc-Iot spece 1 and is responsible for lowering of the alveolar surface tension. .