title: Solution studies of chymotrypsin inhibitor-2 glutamine insertion mutants show no interglutamine interactions.
abstract: Mutants of chymotrypsin inhibitor protein 2 have previously been studied in which 4 or 10 glutamine residues were inserted into the inhibitory loop of the protein between residues 59 and 60, as potential models for the behaviour of glutamine tracts in proteins associated with polyglutamine-expansion neurodegenarative diseases. These mutants form very stable monomers, dimers and trimers. Although the cause of oligomerisation was found to be domain-swapping, it was thought that the glutamine insertions might nevertheless show evidence of weak interglutamine interactions in solution that could mimic those occurring in disease-associated proteins. In the present NMR study, we used steady-state (15)N[(1)H] NOE measurements and chemical shift comparisons to characterise the motional properties of the inserted glutamines in these CI2 mutants. We found the glutamines to be highly mobile, with no evidence of interactions amongst them in either monomers or dimers.
authors.affiliation: M.R.C. Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, United Kingdom.
authors.forename: D J
authors.initials: DJ
authors.lastname: Gordon-Smith
authors.forename: R J
authors.initials: RJ
authors.lastname: Carbajo
authors.forename: K
authors.initials: K
authors.lastname: Stott
authors.forename: D
authors.initials: D
authors.lastname: Neuhaus
mesh_terms: D000595:Amino Acid Sequence; D002918:Chymotrypsin / Q000037:antagonists & inhibitors*; D004355:Drug Stability; D005973:Glutamine / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010455:Peptides / Q000737:chemistry* / Q000235:genetics*; D010940:Plant Proteins; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D020449:Repetitive Sequences, Amino Acid; D015842:Serine Proteinase Inhibitors / Q000737:chemistry* / Q000235:genetics*; D012996:Solutions
chemical_list: D010455:Peptides; D010940:Plant Proteins; D011994:Recombinant Proteins; D015842:Serine Proteinase Inhibitors; D012996:Solutions; C093336:chymotrypsin inhibitor 2; D005973:Glutamine; D002918:Chymotrypsin