title: 1H-NMR assignment and folding of the isolated ribonuclease 21-42 fragment.
abstract: We show in this paper that the isolated bovine ribonuclease 21-42 fragment is able to adopt in water solution a measurable population (14% at 22 degrees C, pH 5.4) of a native-like alpha-helical structure. Strong support for this conclusion is given by the analysis of CD data and 1H chemical shift variations with the temperature and the addition of stabilizing (trifluoroethanol) and denaturing (urea) agents. This results gives experimental support to the idea that native isolated secondary structure elements (at least alpha helices) are, as a rule, partially stable in solution and therefore they can act as independent protein-folding nucleation centers.
authors.affiliation: Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
authors.forename: M A
authors.initials: MA
authors.lastname: Jiménez
authors.forename: M
authors.initials: M
authors.lastname: Rico
authors.forename: J
authors.initials: J
authors.lastname: Herranz
authors.forename: J
authors.initials: J
authors.lastname: Santoro
authors.forename: J L
authors.initials: JL
authors.lastname: Nieto
mesh_terms: D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D009682:Magnetic Resonance Spectroscopy; D010446:Peptide Fragments; D012260:Ribonucleases; D012996:Solutions; D014270:Trifluoroethanol; D014508:Urea; D014867:Water
chemical_list: D010446:Peptide Fragments; D012996:Solutions; D014867:Water; D014270:Trifluoroethanol; D014508:Urea; D012260:Ribonucleases; C022542:ribonuclease S