FEBS Letters | |
An amphipathic helical motif common to tumourolytic polypeptide NK‐lysin and pulmonary surfactant polypeptide SP‐B | |
Curstedt, Tore1  Johansson, Jan2  Andersson, Mats2  Jörnvall, Hans2  | |
[1] Department of Clinical Chemistry, Karolinska Institutet at Danderyd Hospital, S-182 88 Danderyd, Sweden;Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm, Sweden | |
关键词: Lipid-binding polypeptide; Secondary structure; Saposin-like module; CD; circular dichroism; DPC; dodecylphosphocholine; DPPC; 1; 2-dipalmitoyl-sn-glycero-3-phosphocholine; DTT; dithiothreitol; NK; natural killer; PA; palmitic acid; PG; phosphatidylglycerol; SP; surfactant protein; | |
DOI : 10.1016/0014-5793(95)00268-E | |
学科分类:生物化学/生物物理 | |
来源: John Wiley & Sons Ltd. | |
【 摘 要 】
The tumour-lysing and antimicrobial polypeptide NK-lysin and the pulmonary surfactant-associated polypeptide SP-B exhibit 24% residue identities (49% similarities), including six half-cystine residues in the same disulphide bonding pattern, and similar far-UV circular dichroism spectra corresponding to 45–55% α-helix and 20–25% β-sheet structures. From this, we conclude that the conformations of NK-lysin and SP-B are similar. In contrast, the functional properties of the two proteins are dissimilar: SP-B does not exhibit antibacterial activity and NK-lysin does not significantly effect phospholipid spreading at an air/water interface. Saposins, which solubilize lipids and activate lysosomal hydrolases, the pore-forming amoebapores, and parts of acid sphingomyelinase and acyloxyacylhydrolase, also share 18–27% sequence identities with NK-lysin (and SP-B), including the six conserved half-cystine residues. The inclusion of NK-lysin extends the family of saposin-like polypeptides, all members of which appear to interact with lipids. Strictly conserved structural features with implications for helix topology and lipid interactions are observed.
【 授权许可】
Unknown
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