title: The limited proteolysis of tumor necrosis factor-alpha.
abstract: The limited proteolysis of human recombinant TNF-alpha by trypsin yields two stable products resulting from cleavage after Arg6 and Arg44. In solution these two products remain associated together in a trimer with a Stokes' radius slightly greater than the radius of intact TNF-alpha and, therefore, could not be separated from each other under nondenaturing conditions. This limited digest retains at least 20% of the activity of the original TNF-alpha sample, and has a tertiary structure that is similar to that of the native protein by circular dichroism. On the other hand, incorrectly folded, inactive TNF-alpha undergoes extensive digestion following similar treatment with trypsin. These results indicate that the active form of TNF-alpha has a tight core structure which is maintained after N-terminal cleavage and removal.
authors.affiliation: Amgen Inc., Thousand Oaks, California 91320.
authors.forename: L O
authors.initials: LO
authors.lastname: Narhi
authors.forename: M F
authors.initials: MF
authors.lastname: Rhode
authors.forename: P
authors.initials: P
authors.lastname: Hunt
authors.forename: T
authors.initials: T
authors.lastname: Arakawa
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000302:isolation & purification; D011487:Protein Conformation; D012697:Serine Endopeptidases; D014357:Trypsin; D014409:Tumor Necrosis Factor-alpha / Q000302:isolation & purification*
chemical_list: D010446:Peptide Fragments; D014409:Tumor Necrosis Factor-alpha; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; D014357:Trypsin