title: Solution structure and biological activity of recombinant salmon calcitonin S-sulfonated analog.
abstract: Salmon calcitonin S-sulfonated analog (abbreviated as [S-SO(3)(-)]rsCT) was prepared by introducing two sulfonic groups into the side chains of Cys1 and Cys7 of recombinant salmon calcitonin. The hypocalcemic potency of this open-chain analog is 5500IU/mg, which is about 30% higher than that (4500IU/mg) of the wild type. The solution conformation of [S-SO(3)(-)]rsCT was studied in aqueous trifluoroethanol solution by CD, 2D-NMR spectroscopy, and distance geometry calculations. In the mixture of 60% TFE and 40% water, the peptide assumes an amphipathic alpha-helix in the region of residues 4-22, which is one turn longer than that of the native sCT. The structural feature analysis of the peptide revealed the presence of hydrophobic surface composed of five hydrophobic side chains of residues Leu4, Leu9, Leu12, Leu16, and Leu19, and a network of salt-bridges that consisted of a tetrad of oppositely charged side chains (Cys7-SO(3)(-)-Lys11(+)-Glu15(-)-Lys18(+)). The multiple salt bridges resulted in the stabilization of the longer amphipathic alpha-helix. Meanwhile, the higher hypocalcemic potency of the peptide could be attributed to the array of hydrophobic side chains of five leucine residues of the amphipathic alpha-helix.
authors.affiliation: State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, 200032, Shanghai, PR China.
authors.forename: Yuefeng
authors.initials: Y
authors.lastname: Wang
authors.forename: Hong
authors.initials: H
authors.lastname: Dou
authors.forename: Chunyang
authors.initials: C
authors.lastname: Cao
authors.forename: Naixia
authors.initials: N
authors.lastname: Zhang
authors.forename: Jingbiao
authors.initials: J
authors.lastname: Ma
authors.forename: Jifang
authors.initials: J
authors.lastname: Mao
authors.forename: Houming
authors.initials: H
authors.lastname: Wu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002116:Calcitonin / Q000737:chemistry*; D002942:Circular Dichroism; D003545:Cysteine / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007930:Leucine / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008962:Models, Theoretical; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D012474:Salmon; D012492:Salts / Q000494:pharmacology; D013329:Structure-Activity Relationship; D014270:Trifluoroethanol / Q000494:pharmacology
chemical_list: D011994:Recombinant Proteins; D012492:Salts; D014270:Trifluoroethanol; D002116:Calcitonin; D007930:Leucine; D003545:Cysteine