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Comparative Studies of the Binding of Dimeric and Monomeric Enkephalins to Neuroblastoma‐Glioma NG108–15 Cells
Author(s) -
Krumins Solveig A.,
Rodbard David
Publication year - 1985
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1985.tb05480.x
Subject(s) - enkephalin , biology , monomer , amide , stereochemistry , chemistry , receptor , biochemistry , polymer , opioid , organic chemistry
Binding activity of the enkephalin dimer [d‐Ala 2 , Leu 5 ‐NH‐CH 2 ‐ ‐ ] 2 (DPE 2 ) to NG108–15 hybrid cells was compared to that of the monomer [d‐Ala 2 , Leu 5 ]enkephalin amide (DALEA). At 25°C, the values of the apparent affinity constant for DPE 2 , measured to intact and lysed cells and membranes, was 5.0 (±0.09) × 10 9 M −1 for n = 28 experiments, as compared to 0.9 (±0.08) × 10 9 M −1 (n = 16) for DALEA. At 4°C, the binding affinity of DPE 2 decreased by 43% and that of DALEA by 33%. An important difference between the binding of DPE 2 and DALEA was that, after necessary corrections for difference in maximal “bindability” of the respective tritiated enkephalins, the molar binding capacity for DALEA was twofold higher than for DPE 2 , although mutual cross‐displacement studies indicated that binding occurred to one class of noninteracting homogeneous receptors. The binding capacity for intact and lysed cells and membranes was 20 (±2) × 10 − ‐ 11 M for DPE 2 and 43 (±2) × 10 − ‐ 11 M for DALEA. The enkephalin monomers [d‐Ala 2 , d‐Leu 5 ]enkephalin (DADLE) and [d‐Ala 2 , Met 5 ]enkephalin amide (DAMEA) showed binding characteristics similar to those of DALEA.