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Updated: Apr 22, 2026

Genetic and Biochemical Approaches for In Vivo and In Vitro Assessment of Protein Oligomerization: The Ryanodine Receptor Case Study
Published on: July 27, 2016
N-methylthioacetylation of RYYRIK-NH2 with enhanced specific binding affinity and high antagonist activity for
Jinglan Li1, Hirokazu Nishimura, Ayami Matsushima
1Laboratory of Structure–Function Biochemistry, Department of Chemistry, Faculty and Graduate School of Sciences, and Risk Science Research Center, Kyushu University, Fukuoka 812-8581, Japan.
Abstract:
Antagonists of the neuropeptide nociceptin are expected to be potential analgesic and antineuropathic drugs acting on ORL1 GPCR receptors. The peptide library-based antagonist Ac-RYYRIK-NH2 inhibits the nociceptin activity mediated through ORL1, but preserves a considerably high level of agonist activity. We previously reported that the N-terminal acyl group is important for interaction with specific receptors, and developed isovarelyl-RYYRIK-NH2, which exhibits strong antagonist activity with negligible agonist activity. In the present study, in order to obtain a more potent antagonist, we further modified the isovarelyl group by replacing its Cβ atom with an oxygen, nitrogen, or sulfur atom to give the methyl group improved interaction ability. The methyl group bound to such heteroatoms was expected to enhance the hydrophobic interaction between the peptide and the ORL1 receptor. The RYYRIK-NH2 peptide with a methylthioacetyl group, CH3SCH2CO, revealed a higher receptor-binding affinity with strong antagonist activity, and the results suggested the presence of a receptor aromatic group as a complementary residue of this CH3S group.
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