title: Circular dichroism studies on the signal sequence of E. coli alkaline phosphatase indicate the presence of both alpha-helix and beta-structure in hydrophobic environments.
abstract: The conformations of a synthetic peptide corresponding to the signal sequence of E. coli alkaline phosphatase, Lys-Gln-Ser-Thr-Ile-Ala-Leu-Ala-Leu-Leu-Pro-Leu-Leu-Phe-Thr-Pro-Val-Thr- Lys- Ala-OCH3, have been examined in different environments by circular dichroism spectroscopy. In trifluoroethanol, methanol and aqueous mixtures of these solvents, the signal peptide has largely random conformation (approximately 80%) with small amounts of alpha-helix and beta-structure. However, in micellar environment, there is a significant increase in ordered conformation with both alpha-helix and beta-structure being present, unlike in other signal sequences reported in the literature, where only the alpha-helical conformation has been observed. Hence, an alpha-helical conformation may not be as stringent a requirement as overall hydrophobicity for recognition of signal sequences by the cell's export machinery.
mesh_terms: D000469:Alkaline Phosphatase; D000595:Amino Acid Sequence; D002942:Circular Dichroism; D004926:Escherichia coli / Q000201:enzymology*; D046911:Macromolecular Substances; D008433:Mathematics; D000432:Methanol; D008823:Micelles; D011487:Protein Conformation; D021382:Protein Sorting Signals; D014270:Trifluoroethanol
chemical_list: D046911:Macromolecular Substances; D008823:Micelles; D021382:Protein Sorting Signals; D014270:Trifluoroethanol; D000469:Alkaline Phosphatase; D000432:Methanol