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Updated: Aug 17, 2026

Modification and Functionalization of the Guanidine Group by Tailor-made Precursors
Published on: April 27, 2017
[The nature of cation-binding groups in binding sites for [[3H]Tyr1, D-Ala2, D-Leu5]enkephalin]
Abstract:
The influence of pH on binding of labeled stable analog of enkephalin, [3H]Tyr1, D-Ala2, D-Leu5]enkephalin, to high- and low-affinity receptors of rat brain membranes was studied. It was shown that alkali-earth metal ions combine with a deprotonated group (pKa 7,0) of the high-affinity receptor, thereby activating the latter. The effect of cations on the low-affinity enkephalin binding is independent of pH. The presence of phosphate group in the high-affinity binding site, as well as of imidazole residue in the low-affinity binding site was surmised. The latter supposition was supported by data on chemical modification of the membrane preparation with the aid of diethylpyrocarbonate.
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