Neuropeptide Y: Y1 and Y2 affinities of the complete series of analogs with single D-residue substitutions

• Published in: Journal of medicinal chemistry Vol. 36; no. 24; pp. 3802 - 3808
• Main Authors: Kirby, Dean A, Boublik, Jaroslav H, Rivier, Jean E
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-11-1993
• Subjects: Amino Acid Sequence; Biological and medical sciences; Chromatography, High Pressure Liquid; Circular Dichroism; Humans; Medical sciences; Molecular Sequence Data; Neuroblastoma - metabolism; Neuropeptide Y - analogs & derivatives; Neuropeptide Y - chemistry; Neuropeptide Y - metabolism; Neuropharmacology; Neurotransmitters. Neurotransmission. Receptors; Peptidergic system (neuropeptide, opioid peptide, opiates...). Adenosinergic and purinergic systems; Peptides - chemical synthesis; Peptides - chemistry; Peptides - metabolism; Pharmacology. Drug treatments; Protein Conformation; Protein Structure, Secondary; Receptors, Neuropeptide Y - metabolism; Structure-Activity Relationship; Tumor Cells, Cultured; Human; Neuropeptide Y; Peptide hormone; Molecular interaction; Binding site; In vitro; α-Aminoacid; Biological fixation; Chemical modification; Established cell line; Peptidergic receptor; Sympathic nervous system; Biological receptor
• ISSN: 0022-2623; 1520-4804
• DOI: 10.1021/jm00076a007

In an effort to gain insight into the bioactive conformation of neuropeptide Y upon interaction with its receptors, all single-point D-amino acid substituted NPY analogues were prepared, and their Y1 and Y2 receptor binding affinities were evaluated using the human neuroblastoma cell lines, SK-N-MC and SK-N-BE2, respectively. Solid-phase synthesis (Boc strategy) followed by preparative HPLC purification produced analogues of high purity that were characterized by RP-HPLC, AAA, LSIMS, CZE, and optical rotation. Of the 37 isomers (a naturally occurring glycine at position 9 was replaced by Ala and D-Ala), Y1 receptor binding was most perturbed by chiral inversion of residues at the C-terminus (residues 20, 27, 29-35, Ki > or = 300 nM). Substitutions at residues 2-5, 28, and 36 had Ki values ranging from 40 to 260 nM. Substitutions at all other positions yielded analogues with affinities ranging from 1.5 to 20 nM. Binding affinities to the Y2 class of receptors all measured in the low or sub-nanomolar concentrations, with the exception of C-terminally modified isomers (residues 30-35). Only [D-Arg33]- and [D-Gln34]NPY displayed no measurable binding affinity to Y2 receptors at the highest concentration tested (1000 nM). Representative analogues were selected on the basis of their binding affinities and position in the sequence for structural analysis using circular dichroism (CD) spectroscopy. Of the nine peptide evaluated ([D-Pro5]-, [Ala9]-, [D-Glu10]-, [D-Asp11]-, [D-Ala18]-, [D-Tyr20]-, [D-Tyr27]-, and [D-Arg33]NPY), only [D-Tyr27]NPY expressed a definitive correlation between loss of binding affinity and disruption of secondary structure by having the propensity to form beta-sheets at the expense of alpha-helical content. It was concluded that although the incorporation of a single D-amino acid within the sequence of NPY may confer a conformational perturbation, the receptor interaction was only affected when certain critical residues were modified, findings that provide a basis for the identification of the binding pharmacophore of NPY.