title: The disulfide bond pairing of the pheromones Er-1 and Er-2 of the ciliated protozoan Euplotes raikovi.
abstract: The disulfide pairings of the two Euplotes raikovi pheromones Er-1 and Er-2 have been determined by chemical and mass spectrometric analyses. Cystine-linked peptides from thermolytic digestions of the native molecules were purified by reverse-phase high performance liquid chromatography and identified in the known sequences to make the assignments. The same pairing, Cys(I)-Cys(IV), Cys(II)-Cys(VI), and Cys(III)-Cys(V), was found in both pheromones, suggesting that this pattern occurs commonly throughout this family of molecules. This arrangement of disulfides indicates that the three-dimensional structure is defined by three loops, which can vary in size and charge distribution from one pheromone to another.
authors.affiliation: Department of Biological Chemistry, College of Medicine, University of California, Irvine 92717.
authors.forename: A E
authors.initials: AE
authors.lastname: Stewart
authors.forename: S
authors.initials: S
authors.lastname: Raffioni
authors.forename: T
authors.initials: T
authors.lastname: Chaudhary
authors.forename: B T
authors.initials: BT
authors.lastname: Chait
authors.forename: P
authors.initials: P
authors.lastname: Luporini
authors.forename: R A
authors.initials: RA
authors.lastname: Bradshaw
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003553:Cystine; D004220:Disulfides / Q000032:analysis; D016812:Euplotes / Q000502:physiology*; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000302:isolation & purification; D010675:Pheromones / Q000737:chemistry*; D011487:Protein Conformation; D015800:Protozoan Proteins / Q000737:chemistry*
chemical_list: D004220:Disulfides; D008565:Membrane Proteins; D010446:Peptide Fragments; D010675:Pheromones; D015800:Protozoan Proteins; C081617:mating pheromone 2, Euplotes raikovi; C057783:mating pheromone Er-1, Euplotes raikovi; D003553:Cystine