title: Characterization of human and bovine phosphatidylethanolamine-binding protein (PEBP/RKIP) interactions with morphine and morphine-glucuronides determined by noncovalent mass spectrometry.
abstract: BACKGROUND
  The phosphatidylethanolamine-binding protein (PEBP/RKIP), initially found to bind phosphatidylethanolamine (PE), has been shown to be associated with morphine derivatives. Our recent study on bovine primary chromaffin cells showed that inside secretory granules, PEBP is noncovalently associated to endogenous morphine-6-glucuronide (M6G), a highly analgesic morphine metabolite. During stress, M6G-PEBP complexes may be released into circulation to target peripheral opioid receptors. We now report the investigation of PEBP binding properties towards morphine and morphine analogs.
  
  
  METHODS
  Noncovalent electrospray ionization mass spectrometry (ESI-MS) was used to investigate bovine and human PEBP binding properties towards morphine and morphine-glucuronides.
  
  
  RESULTS
  We describe for the first time that: (i) PEBP directly interacts with morphine glucuronides (M3G and M6G) but not with morphine, (ii) that the presence of a glucuronide group either on the 3rd or the 6th morphine's carbon does not affect these interactions, (iii) that M6G binds PEBP in a similar manner as the reference ligand PE and (iv) that PEBP displays a similar affinity for PE, M6G and M3G.
  
  
  CONCLUSIONS
  Our results suggest that PEBP might protect M6G following its secretion into blood, leading to a longer half life. This study highlights the potentialities of ESI-MS to validate / invalidate the formation of protein: ligand noncovalent complexes when low affinity binders (i.e., compounds with affinities lower than 10(3) M(-1)) are concerned.
authors: Laboratoire de Spectrométrie de Masse, BioOrganique (LSMBO), IPHC-DSA, University of Strasbourg UDS, CNRS UMR7178, Strasbourg, France.
authors: Cédric
authors: C
authors: Atmanene
authors: Alexis
authors: A
authors: Laux
authors: Elise
authors: E
authors: Glattard
authors: Arnaud
authors: A
authors: Muller
authors: Françoise
authors: F
authors: Schoentgen
authors: Marie-Hélène
authors: MH
authors: Metz-Boutigue
authors: Dominique
authors: D
authors: Aunis
authors: Alain
authors: A
authors: Van Dorsselaer
authors: George B
authors: GB
authors: Stefano
authors: Sarah
authors: S
authors: Sanglier-Cianférani
authors: Yannick
authors: Y
authors: Goumon
mesh_terms: D000818:Animals; D002417:Cattle; D006801:Humans; D013058:Mass Spectrometry; D009022:Morphine Derivatives / Q000737:chemistry / Q000378:metabolism*; D049488:Phosphatidylethanolamine Binding Protein / Q000378:metabolism*; D010714:Phosphatidylethanolamines / Q000378:metabolism; D017186:Titrimetry
chemical_list: D009022:Morphine Derivatives; D049488:Phosphatidylethanolamine Binding Protein; D010714:Phosphatidylethanolamines; C483858:phosphatidylethanolamine; C035349:morphine-6-glucuronide