Comparative binding properties of linear and cyclic delta-selective enkephalin analogues: [3H]-[D-Thr2, Leu5] enkephalyl-Thr6 and [3H]-[D-Pen2, D-Pen5] enkephalin.
The range of delta-selectivity of linear and cyclic analogues of enkephalin in rat brain was found to be: [D-Pen2, L-Pen5] enkephalin (DPLPE) greater than [D-Pen2, D-Pen5] enkephalin (DPDPE) greater than [D-Thr2, Leu5] enkephalyl-Thr6 (DTLET) greater than [D-Ser2, Leu5] enkephalyl-Thr6 (DSLET). Saturation experiments performed with [3H]DPDPE and [3H]DTLET in NG108-15 cells and rat brain showed similar binding capacities for both the ligands, but the delta-affinity of [3H]DTLET (KD approximately 1.2 nM) was much better than that of [3H]DPDPE (KD approximately 7.2 nM). The rather low delta-affinity of DPDPE induced high experimental errors cancelling the benefit of its better delta-selectivity. Binding experiments in rat or guinea-pig brains showed, in both cases, the better delta-selectivity of [3H]DTLET compared to [3H]DSLET. The former peptide remains at this time the most appropriate radioactive probe for binding studies of delta-receptor.
Delay-Goyet
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P
Zajac
J M
JM
Rigaudy
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P
Foucaud
B
B
Roques
B P
BP
D000818:Animals; D001921:Brain / Q000378:metabolism; D002460:Cell Line; D020881:Enkephalin, D-Penicillamine (2,5)-; D004745:Enkephalins / Q000378:metabolism*; D005910:Glioma / Q000378:metabolism; D006168:Guinea Pigs; D007536:Isomerism; D007700:Kinetics; D009447:Neuroblastoma / Q000378:metabolism; D009842:Oligopeptides / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000378:metabolism*; D017465:Receptors, Opioid, delta
D004745:Enkephalins; D009842:Oligopeptides; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; C037653:deltakephalin; D020881:Enkephalin, D-Penicillamine (2,5)-