Secondary Structure and Lipid Interactions of the N-Terminal Segment of Pulmonary Surfactant SP-C in Langmuir Films:  IR Reflection−Absorption Spectroscopy and Surface Pressure Studies†

Biochemistry ◽  
2002 ◽  
Vol 41 (26) ◽  
pp. 8385-8395 ◽  
Author(s):  
Xiaohong Bi ◽  
Carol R. Flach ◽  
Jesus Pérez-Gil ◽  
Inés Plasencia ◽  
David Andreu ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Absorption Spectroscopy ◽  
Surface Pressure ◽  
Pulmonary Surfactant ◽  
Terminal Segment ◽  
Langmuir Films ◽  
Lipid Interactions ◽  
Ir Reflection

scholarly journals Secondary structure and biophysical activity of synthetic analogues of the pulmonary surfactant polypeptide SP-C

1995 ◽  
Vol 307 (2) ◽  
pp. 535-541 ◽  
Author(s):  
J Johansson ◽  
G Nilsson ◽  
R Strömberg ◽  
B Robertson ◽  
H Jörnvall ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Pulmonary Surfactant ◽  
Transmembrane Helix ◽  
Helical Structure ◽  
Helical Conformation ◽  
Synthetic Analogues ◽  
Charged Amino Acids ◽  
Phospholipid Micelles ◽  
Helical Content ◽  
Biophysical Activity

Native pulmonary-surfactant-associated lipopolypeptide SP-C, its chemically depalmitoylated form and several synthetic analogues lacking the palmitoylcysteine residues were analysed for secondary structure in phospholipid micelles and for biophysical activity in 1,2-dipalmitoyl-sn-glycero-3- phosphocholine/phosphatidylglycerol/palmitic acid (68:22:9, by wt.). Compared with the native molecule, with the entire poly-valyl part in a known alpha-helical conformation, depalmitoylated SP-C was found to be still mainly alpha-helical, but with an approx. 20% decrease in the helical content. A synthetic hybrid polypeptide where the entire poly-valyl alpha-helical part of native SP-C had been replaced with the amino acid sequence of a transmembrane helix of bacteriorhodopsin is also predominantly alpha-helical. In contrast, synthetic SP-C analogues lacking only the palmitoyl groups, by replacement of the palmitoylcysteine residues with cysteine, phenylalanine or serine, or lacking the positively charged amino acids by replacement with alanine, are considerably less alpha-helical than both native and depalmitoylated SP-C. The data indicate that the SP-C palmitoyl groups are important for maintenance of the alpha-helical conformation in parts of the polypeptide, and that the poly-valyl alpha-helical conformation is not fully formed in synthetic SP-C polypeptides. Furthermore, the helical structure of both native and depalmitoylated SP-C in dodecylphosphocholine micelles is very resistant to thermal denaturation, exhibiting ordered structure at 90 degrees C. The alpha-helical content grossly parallels the peptide-induced acceleration of the spreading of phospholipids at an air/water interface and the increase of surface pressure. The data suggest that the alpha-helical conformation itself, rather than just the covalent structure, is of prime importance for the biological function of synthetic pulmonary-surfactant peptides.

scholarly journals Effect of N- and C-Terminal Amino Acids on the Interfacial Binding Properties of Phospholipase D from Vibrio parahaemolyticus

2018 ◽  
Vol 19 (8) ◽  
pp. 2447
Author(s):  
Fanghua Wang ◽  
Ruixia Wei ◽  
Abdelkarim Abousalham ◽  
Wuchong Chen ◽  
Bo Yang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Secondary Structure ◽  
Phospholipase D ◽  
Vibrio Parahaemolyticus ◽  
Terminal Segment ◽  
Amino Acid Sequences ◽  
Loop Structure ◽  
Binding Properties ◽  
Phospholipid Monolayers ◽  
Terminal Amino

The effects of N-terminal (1–34 amino acids) and C-terminal (434–487 amino acids) amino acid sequences on the interfacial binding properties of Phospholipase D from Vibrio parahaemolyticus (VpPLD) were characterized by using monomolecular film technology. Online tools allowed the prediction of the secondary structure of the target N- and C-terminal VpPLD sequences. Various truncated forms of VpPLD with different N- or C-terminal deletions were designed, based on their secondary structure, and their membrane binding properties were examined. The analysis of the maximum insertion pressure (MIP) and synergy factor “a” indicated that the loop structure (1–25 amino acids) in the N-terminal segment of VpPLD had a positive effect on the binding of VpPLD to phospholipid monolayers, especially to 1,2-dimyristoyl-sn-glycero-3-phosphoserine and 1,2-dimyristoyl-sn-glycero-3-phosphocholine. The deletion affecting the N-terminus loop structure caused a significant decrease of the MIP and synergy factor a of the protein for these phospholipid monolayers. Conversely, the deletion of the helix structure (26–34 amino acids) basically had no influence on the binding of VpPLD to phospholipid monolayers. The deletion of the C-terminal amino acids 434–487 did not significantly change the binding selectivity of VpPLD for the various phospholipid monolayer tested here. However, a significant increase of the MIP value for all the phospholipid monolayers strongly indicated that the three-strand segment (434–469 amino acids) had a great negative effect on the interfacial binding to these phospholipid monolayers. The deletion of this peptide caused a significantly greater insertion of the protein into the phospholipid monolayers examined. The present study provides detailed information on the effect of the N- and C-terminal segments of VpPLD on the interfacial binding properties of the enzyme and improves our understanding of the interactions between this enzyme and cell membranes.

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