title: Site Covalent Modification of Methionyl Peptides for the Production of FRET Complexes.
abstract: Flax cyclic peptides (orbitides, linusorbs (LOs)) [1-8-NαC],[1-MetO2]-linusorb B1 ([MetO2]-LO1) and [1-9-NαC],[1-MetO2]-linusorb B2 ([MetO2]-LO2) are biologically active. These LOs lack active nuclei commonly used in peptide modification. We have developed reactions to activate methionine methyl sulphide to produce stable derivatives. In these reactions, LOs are converted to sulfonium intermediates and subsequently to derivatives containing active nuclei while preserving their fundamental structures. The reaction conditions preserved cyclic peptide fundamental structure and organic solvent solubility. [Met]-LO1 and [Met]-LO2 analogues containing activated groups (-CN, -COOEt, and -NH2 ) in the form of methionine, methionine (S)-oxide, and methionine (S,S)-dioxide amino acids were synthesized and characterized by LCMS and 1D and 2D NMR spectroscopy. Coumarin orbitide complexes produced in this manner bind Eu(3+) yielding FRET compounds that absorb energy through coumarin antennae and emit photons at lanthanide wavelengths.
authors.affiliation: Plant Sciences, University of Saskatchewan, Saskatoon, SK (Canada). pramodkumar.jadhav@usask.ca.
authors.forename: Pramodkumar D
authors.initials: PD
authors.lastname: Jadhav
authors.affiliation: Plant Sciences, University of Saskatchewan, Saskatoon, SK (Canada).
authors.forename: Jianheng
authors.initials: J
authors.lastname: Shen
authors.affiliation: Saskatchewan Structural Sciences Centre, University of Saskatchewan, Saskatoon, SK (Canada).
authors.forename: Ramaswami
authors.initials: R
authors.lastname: Sammynaiken
authors.affiliation: Plant Sciences, University of Saskatchewan, Saskatoon, SK (Canada). martin.reaney@usask.ca.|Guangdong Saskatchewan Oilseed Joint Laboratory, Department of Food Science and Engineering, Jinan University, Guangzhou, Guangdong 510632 (People's Republic of China). martin.reaney@usask.ca.
authors.forename: Martin J T
authors.initials: MJ
authors.lastname: Reaney
mesh_terms: D000478:Alkylation; D000596:Amino Acids / Q000737:chemistry*; D001686:Biological Phenomena; D003374:Coumarins / Q000737:chemistry*; D005063:Europium / Q000737:chemistry*; D028581:Lanthanoid Series Elements / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008715:Methionine / Q000031:analogs & derivatives / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D010456:Peptides, Cyclic / Q000737:chemistry*; D017785:Photons
chemical_list: D000596:Amino Acids; D003374:Coumarins; D028581:Lanthanoid Series Elements; D010455:Peptides; D010456:Peptides, Cyclic; D005063:Europium; C030123:coumarin; D008715:Methionine
keywords: FRET; alkylation; lanthanides; methionine; natural products; peptides