Role of hydrogen bonding in ligand interaction with the N-methyl-D-aspartate receptor ion channel.
Displacement of [3H]MK-801 (dizocilpine, 1) binding to rat brain membranes has been used to evaluate the affinities of novel dibenzocycloalkenimines related to 1 for the ion channel binding site (also known as the phencyclidine or PCP receptor) on the N-methyl-D-aspartate (NMDA) subtype of excitory amino acid receptor. In common with many other agents having actions in the central nervous system, these compounds contain a hydrophobic aromatic moiety and a basic nitrogen atom. The conformational rigidity of these ligands provides a unique opportunity to evaluate the importance of specific geometrical properties that influence active-site recognition, in particular the role of the nitrogen atom in hydrogen-bonding interactions. The relative affinities (IC50s) of hydrocarbon-substituted analogues of 1 and ring homologated cyclooctenimines illustrate the importance of size-limited hydrophobic binding of both aryl rings and of the quaternary C-5 methyl group. Analysis of the binding of a series of the 10 available structurally rigid dibenzoazabicyclo[x.y.z]alkanes, by using molecular modeling techniques, uncovered a highly significant correlation between affinity and a proposed ligand-active site hydrogen bonding vector (r = 0.950, p less than 0.001). These results are used to generate a pharmacophore of the MK-801 recognition site/PCP receptor, which accounts for the binding of all of the known ligands.
Leeson
P D
PD
Merck Sharp Laboratory, Neuroscience Research Centre, Harlow, Essex, U.K.
Carling
R W
RW
James
K
K
Smith
J D
JD
Moore
K W
KW
Wong
E H
EH
Baker
R
R
D000818:Animals; D000927:Anticonvulsants / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology*; D001665:Binding Sites; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D003986:Dibenzocycloheptenes / Q000378:metabolism; D016291:Dizocilpine Maleate; D006860:Hydrogen Bonding; D007473:Ion Channels / Q000187:drug effects; D008024:Ligands; D008958:Models, Molecular; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter / Q000187:drug effects* / Q000378:metabolism; D013329:Structure-Activity Relationship; D014316:Tritium
D000927:Anticonvulsants; D003986:Dibenzocycloheptenes; D007473:Ion Channels; D008024:Ligands; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter; D014316:Tritium; D016291:Dizocilpine Maleate