title: A novel soluble protein factor with non-opioid dynorphin A-binding activity.
abstract: A novel soluble non-opioid dynorphin A-binding factor (DABF) was identified and characterized in neuronal cell lines, rat spinal cord, and brain. DABF binds dynorphin A(1-17), dynorphin A(2-17), and the 32 amino acid prodynorphin fragment big dynorphin consisting of dynorphin A and B, but not other opioid and non-opioid peptides, opiates, and benzomorphans. The IC50 for dynorphin A(1-17), dynorphin A(2-17), and big dynorphin is in the 5-10 nM range. Using dynorphin A and big dynorphin fragments a binding epitope was mapped to dynorphin A(6-13). DABF has a molecular mass of about 70 kDa. SH-groups are apparently involved in the binding of dynorphin A since p-hydroxy-mercuribenzoic acid inhibited this process. Upon interaction with DABF dynorphin A was converted into Leu-enkephalin, which remained bound to the protein. These data suggest that DABF functions as an oligopeptidase that forms stable and specific complexes with dynorphin A. The presence of DABF in brain structures and other tissues with low level of prodynorphin expression suggests that DABF as an oligopeptidase may degrade other peptides. Dynorphin A at the sites of its release in the CNS may attenuate this degradation as a competitor when it specifically binds to the enzyme.
authors.affiliation: Alcohol and Drug Dependence Research Section, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Zoya
authors.initials: Z
authors.lastname: Marinova
authors.forename: Tatjana
authors.initials: T
authors.lastname: Yakovleva
authors.forename: Matthias F
authors.initials: MF
authors.lastname: Melzig
authors.forename: Mathias
authors.initials: M
authors.lastname: Hallberg
authors.forename: Ingrid
authors.initials: I
authors.lastname: Nylander
authors.forename: Kallol
authors.initials: K
authors.lastname: Ray
authors.forename: David W
authors.initials: DW
authors.lastname: Rodgers
authors.forename: Kurt F
authors.initials: KF
authors.lastname: Hauser
authors.forename: Tomas J
authors.initials: TJ
authors.lastname: Ekström
authors.forename: Georgy
authors.initials: G
authors.lastname: Bakalkin
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D018288:Carcinoma, Small Cell; D002352:Carrier Proteins / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002822:Choriocarcinoma; D003634:DDT / Q000494:pharmacology; D004399:Dynorphins / Q000378:metabolism*; D006801:Humans; D006902:Hydroxymercuribenzoates / Q000494:pharmacology; D007700:Kinetics; D008175:Lung Neoplasms; D051379:Mice; D008815:Mice, Inbred Strains; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009447:Neuroblastoma; D009474:Neurons / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology
chemical_list: D002352:Carrier Proteins; D006902:Hydroxymercuribenzoates; D009419:Nerve Tissue Proteins; D011480:Protease Inhibitors; C030601:4-hydroxymercuribenzoate; D004399:Dynorphins; D003634:DDT