title: Minithioredoxin: a folded and functional peptide fragment of thioredoxin.
abstract: A peptide fragment comprising the first 83 residues from the N-terminus of E. coli thioredoxin is purified by hydroxylamine cleavage of the intact protein. At physiological pH, the secondary and tertiary structure contents of the peptide are 70 and 35%, respectively, compared to the intact protein. Peptide 83 is able to display dual biological functions of thioredoxin, namely, a substrate for the enzyme E. coli thioredoxin-reductase and a processivity factor of T7 DNA polymerase. At present, peptide 83 represents the minimum functional and folding unit of thioredoxin. The highly conserved residue Phe 81 appears to play an important role in the folding of peptide 83, as judged from the packing analysis. Peptide 83 also mimics a particular kinetic folding intermediate of thioredoxin in terms of spectral properties and may serve as an equilibrium peptide model for the former.
authors.affiliation: Molecular Biophysics Unit (MBU), Indian Institute of Science (IISc), Bangalore, Pin-, 560 012, India. akg@mbu.iisc.ernet.in
authors.forename: A K
authors.initials: AK
authors.lastname: Ghoshal
mesh_terms: D000817:Anilino Naphthalenesulfonates; D002942:Circular Dichroism; D004228:Dithionitrobenzoic Acid / Q000737:chemistry; D004229:Dithiothreitol / Q000737:chemistry; D004926:Escherichia coli / Q000737:chemistry*; D005456:Fluorescent Dyes; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D010649:Phenylalanine / Q000737:chemistry; D017510:Protein Folding; D013050:Spectrometry, Fluorescence; D013439:Sulfhydryl Reagents / Q000737:chemistry; D013880:Thioredoxin-Disulfide Reductase / Q000378:metabolism; D013879:Thioredoxins / Q000737:chemistry* / Q000378:metabolism; D014364:Tryptophan / Q000737:chemistry
chemical_list: D000817:Anilino Naphthalenesulfonates; D005456:Fluorescent Dyes; D010446:Peptide Fragments; D013439:Sulfhydryl Reagents; D010649:Phenylalanine; D013879:Thioredoxins; C027132:1-anilino-8-naphthalenesulfonate; D014364:Tryptophan; D004228:Dithionitrobenzoic Acid; D013880:Thioredoxin-Disulfide Reductase; D004229:Dithiothreitol