title: Dynorphin A(1-17) biotransformation in striatum of freely moving rats using microdialysis and matrix-assisted laser desorption/ionization mass spectrometry.
abstract: The biotransformation of the opioid peptide dynorphin A(1-17) was investigated in striatum of freely moving Fischer rats, by direct infusion of this peptide, followed by recovery of the resulting biotransformation products via microdialysis and identification using matrix-assisted laser desorption/ionization mass spectrometry. The observed peptides are consistent with enzymatic cleavage at the Arg7-Ile8 position of dynorphin A(1-17), followed by terminal degradation of the resulting dynorphin A(1-7) and dynorphin A(8-17) peptides. Unexpectedly, novel post-translational modifications were found on C-terminal fragments of dynorphin A(1-17). Using tandem mass spectrometry, a covalent modification of mass 172 Da, the nature of which is not understood, was found on the tryptophan residue of C-terminal fragments (Trp14). Additional modifications, of mass 42 and 113 Da, were also found on the N-terminus (Ile8 or Pro10) of these same C-terminal fragments. The role of these modifications of C-terminal fragments has not yet been characterized.
authors.affiliation: Laboratory of the Biology of Addictive Diseases, The Rockefeller University, New York, New York, USA. reedb@rockefeller.edu
authors.forename: Brian
authors.initials: B
authors.lastname: Reed
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Brian T
authors.initials: BT
authors.lastname: Chait
authors.forename: Mary Jeanne
authors.initials: MJ
authors.lastname: Kreek
mesh_terms: D000818:Animals; D001711:Biotransformation; D003342:Corpus Striatum / Q000378:metabolism*; D004399:Dynorphins / Q000032:analysis / Q000378:metabolism / Q000493:pharmacokinetics*; D017551:Microdialysis; D010446:Peptide Fragments / Q000032:analysis / Q000096:biosynthesis; D011499:Protein Processing, Post-Translational; D051381:Rats; D011916:Rats, Inbred F344; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014364:Tryptophan / Q000032:analysis / Q000378:metabolism; D014851:Wakefulness
chemical_list: D010446:Peptide Fragments; D004399:Dynorphins; D014364:Tryptophan