Transformation of a κ-Opioid Receptor Antagonist to a κ-Agonist by Transfer of a Guanidinium Group from the 5‘- to 6‘-Position of Naltrindole
摘要:
The importance of the indole scaffold of GNTI 3 in directing its address (5'-guanidinium group) to associate with the Glu297 residue of the Ic-opioid receptor was investigated by the synthesis and biological evaluation of its 4'- (4a), 6'- (4b), and 7'- (4c) regioisomers. The finding that only the 5'-regioisomer (GNTI) possessed potent K-opioid antagonist activity and high affinity at K-receptors illustrates the importance of the 5'-position in orienting the guanidinium group to the proper recognition locus (Glu 297) for potent K-antagonist activity. The discovery that the 6'-regioisomer of GNTI was a potent K-agonist, together with the results of site-directed mutagenesis studies that are consistent with association between the 6'-guanidinium group and Glu297, suggest that the transition from an inactive to an active state of the,c-receptor involves a conformational change of TM6. We propose that association of the 6'-guanidinium group of 4b with Glu297 promotes axial rotational motion of transmembrane helix VI which leads to receptor activation via a conformational change of inner loop 3.
Transformation of a κ-Opioid Receptor Antagonist to a κ-Agonist by Transfer of a Guanidinium Group from the 5‘- to 6‘-Position of Naltrindole
摘要:
The importance of the indole scaffold of GNTI 3 in directing its address (5'-guanidinium group) to associate with the Glu297 residue of the Ic-opioid receptor was investigated by the synthesis and biological evaluation of its 4'- (4a), 6'- (4b), and 7'- (4c) regioisomers. The finding that only the 5'-regioisomer (GNTI) possessed potent K-opioid antagonist activity and high affinity at K-receptors illustrates the importance of the 5'-position in orienting the guanidinium group to the proper recognition locus (Glu 297) for potent K-antagonist activity. The discovery that the 6'-regioisomer of GNTI was a potent K-agonist, together with the results of site-directed mutagenesis studies that are consistent with association between the 6'-guanidinium group and Glu297, suggest that the transition from an inactive to an active state of the,c-receptor involves a conformational change of TM6. We propose that association of the 6'-guanidinium group of 4b with Glu297 promotes axial rotational motion of transmembrane helix VI which leads to receptor activation via a conformational change of inner loop 3.
Transformation of a κ-Opioid Receptor Antagonist to a κ-Agonist by Transfer of a Guanidinium Group from the 5‘- to 6‘-Position of Naltrindole
作者:Shiv Kumar Sharma、Robert M. Jones、Thomas G. Metzger、David M. Ferguson、Philip S. Portoghese
DOI:10.1021/jm010095v
日期:2001.6.1
The importance of the indole scaffold of GNTI 3 in directing its address (5'-guanidinium group) to associate with the Glu297 residue of the Ic-opioid receptor was investigated by the synthesis and biological evaluation of its 4'- (4a), 6'- (4b), and 7'- (4c) regioisomers. The finding that only the 5'-regioisomer (GNTI) possessed potent K-opioid antagonist activity and high affinity at K-receptors illustrates the importance of the 5'-position in orienting the guanidinium group to the proper recognition locus (Glu 297) for potent K-antagonist activity. The discovery that the 6'-regioisomer of GNTI was a potent K-agonist, together with the results of site-directed mutagenesis studies that are consistent with association between the 6'-guanidinium group and Glu297, suggest that the transition from an inactive to an active state of the,c-receptor involves a conformational change of TM6. We propose that association of the 6'-guanidinium group of 4b with Glu297 promotes axial rotational motion of transmembrane helix VI which leads to receptor activation via a conformational change of inner loop 3.