View source for 1ssz


==Conformational Mapping of Mini-B: An N-terminal/C-terminal Construct of Surfactant Protein B Using 13C-Enhanced Fourier Transform Infrared (FTIR) Spectroscopy==
<StructureSection load='1ssz' size='340' side='right'caption='[[1ssz]]' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1ssz]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1SSZ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1SSZ FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Infrared spectroscopy, 10 models</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1ssz FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1ssz OCA], [https://pdbe.org/1ssz PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1ssz RCSB], [https://www.ebi.ac.uk/pdbsum/1ssz PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1ssz ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/PSPB_HUMAN PSPB_HUMAN] Defects in SFTPB are the cause of pulmonary surfactant metabolism dysfunction type 1 (SMDP1) [MIM:[https://omim.org/entry/265120 265120]; also called pulmonary alveolar proteinosis due to surfactant protein B deficiency. A rare lung disorder due to impaired surfactant homeostasis. It is characterized by alveolar filling with floccular material that stains positive using the periodic acid-Schiff method and is derived from surfactant phospholipids and protein components. Excessive lipoproteins accumulation in the alveoli results in severe respiratory distress.<ref>PMID:7491219</ref>   Genetic variations in SFTPB are a cause of susceptibility to respiratory distress syndrome in premature infants (RDS) [MIM:[https://omim.org/entry/267450 267450]. RDS is a lung disease affecting usually premature newborn infants. It is characterized by deficient gas exchange, diffuse atelectasis, high-permeability lung edema and fibrin-rich alveolar deposits called 'hyaline membranes'. Note=A variation Ile to Thr at position 131 influences the association between specific alleles of SFTPA1 and respiratory distress syndrome in premature infants.<ref>PMID:11063734</ref> 
== Function ==
[https://www.uniprot.org/uniprot/PSPB_HUMAN PSPB_HUMAN] Pulmonary surfactant-associated proteins promote alveolar stability by lowering the surface tension at the air-liquid interface in the peripheral air spaces. SP-B increases the collapse pressure of palmitic acid to nearly 70 millinewtons per meter.
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== Publication Abstract from PubMed ==
Surfactant protein B (SP-B) is essential for normal lung surfactant function. Theoretical models predict that the disulfide cross-linked, N- and C-terminal domains of SP-B fold as charged amphipathic helices, and suggest that these adjacent helices participate in critical surfactant activities. This hypothesis is tested using a disulfide-linked construct (Mini-B) based on the primary sequences of the N- and C-terminal domains. Consistent with theoretical predictions of the full-length protein, both isotope-enhanced Fourier transform infrared (FTIR) spectroscopy and molecular modeling confirm the presence of charged amphipathic alpha-helices in Mini-B. Similar to that observed with native SP-B, Mini-B in model surfactant lipid mixtures exhibits marked in vitro activity, with spread films showing near-zero minimum surface tensions during cycling using captive bubble surfactometry. In vivo, Mini-B shows oxygenation and dynamic compliance that compare favorably with that of full-length SP-B. Mini-B variants (i.e. reduced disulfides or cationic residues replaced by uncharged residues) or Mini-B fragments (i.e. unlinked N- and C-terminal domains) produced greatly attenuated in vivo and in vitro surfactant properties. Hence, the combination of structure and charge for the amphipathic alpha-helical N- and C-terminal domains are key to SP-B function.

The role of charged amphipathic helices in the structure and function of surfactant protein B.,Waring AJ, Walther FJ, Gordon LM, Hernandez-Juviel JM, Hong T, Sherman MA, Alonso C, Alig T, Braun A, Bacon D, Zasadzinski JA J Pept Res. 2005 Dec;66(6):364-74. PMID:16316452<ref>PMID:16316452</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 1ssz" style="background-color:#fffaf0;"></div>

==See Also==
*[[Alpha-lytic protease 3D structures|Alpha-lytic protease 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Alig T]]
[[Category: Alonso C]]
[[Category: Bacon D]]
[[Category: Braun A]]
[[Category: Gordon LM]]
[[Category: Hernandez-Juviel JM]]
[[Category: Hong T]]
[[Category: Sherman MA]]
[[Category: Walther FJ]]
[[Category: Waring AJ]]
[[Category: Zasadzinski JA]]