title: Studies on dissociation of mouse prolactin from mouse hepatic receptors.
abstract: The influence of pH, temperature, ethylene glycol, urea, chaotropic anions and excess unlabelled secreted mouse prolactin (smPRL) on the dissociation kinetics of 125I-iodosmPRL from mouse hepatic receptors was investigated. The destabilization of smPRL-receptor complexes by chaotropic anions followed the typical trend of the Hofmeister series: I- greater than Br- greater than Cl- greater than F-. Increasing the temperature of the dissociation reaction from 8 degrees C to 23 degrees C and 30 degrees C caused partial dissociation of 125I-iodosmPRL-receptor complexes. Dissociation of 125I-iodosmPRL from mouse hepatic receptors was pH dependent, with the slowest rate of dissociation occurring at pH 8 and the fastest rate of dissociation occurring at pH 5 and 6. Both ethylene glycol and urea accelerated the rate of dissociation of 125I-iodosmPRL from mouse hepatic receptors in a concentration-dependent manner. Dissociation of 125I-iodosmPRL from mouse hepatic receptors was 6-fold faster in the presence of excess unlabelled smPRL than in its absence. The results of these investigations suggest that both protonation/de-protonation reactions and hydrophobic interactions play important roles in stabilizing the smPRL-receptor complex. In addition, they suggest that cooperative interactions may be involved in the binding of smPRL to mouse hepatic receptors.
mesh_terms: D000818:Animals; D000838:Anions; D002462:Cell Membrane / Q000378:metabolism; D005260:Female; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D051379:Mice; D011247:Pregnancy; D011388:Prolactin / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011981:Receptors, Prolactin; D013816:Thermodynamics
chemical_list: D000838:Anions; D011956:Receptors, Cell Surface; D011981:Receptors, Prolactin; D011388:Prolactin