Elsevier

Peptides

Volume 15, Issue 7, 1994, Pages 1297-1302
Peptides

Article
Synthesis and biological evaluation of α-MSH analogues substituted with alanine

https://doi.org/10.1016/0196-9781(94)90157-0Get rights and content

Abstract

The influence of single amino acid replacements by alanine on the binding affinity and biological activity of α-MSH in B16 murine melanoma cells has been studied systematically. α-MSH analogues were synthesized by solid-phase peptide synthesis and their binding affinities to the melanocortin receptor expressed by B16 mouse melanoma cells were determined using a radioreceptor assay. Biological activity of the analogues was determined by measuring tyrosinase stimulation. Relative activity and affinity data were generally in agreement with earlier results using terminal deletion fragments of α-MSH, but the alanine scan revealed important new insights into the role of individual residues. The three terminal amino acids at either end were not necessary for binding or activity, with amino acids 4–9 forming a core sequence required for receptor binding and triggering of the biological response. It was observed that replacement of the glutamic acid residue in position 5 was possible without loss of affinity or activity, whereas replacement of Met4 resulted in a 100-fold loss of binding affinity and biological activity. Each residue within the conserved melanocortin sequence His-Phe-Arg-Trp was shown to be essential with Phe7, Arg8, and Trp9 being the most sensitive to replacement by alanine. Generally, there was a rank correlation between binding affinity and tyrosinase stimulation within the group of analogues studied. Tyrosinase activity was less affected by alanine substitution than binding affinity, which suggests that full receptor binding is not required for maximum biological response.

References (31)

  • F. Al-Obeidi et al.

    Potent and prolonged acting cyclic lactam analogues of α-melanotropin: Design based on molecular dynamics

    J. Med. Chem.

    (1989)
  • E. Atherton et al.

    Solid-phase peptide synthesis—a practical approach

    (1989)
  • A.G. Beck-Sickinger et al.

    Neuropeptide Y: Identification of the binding site

    Int. J. Pept. Protein Res.

    (1990)
  • J. Blake et al.

    Solid-phase synthesis of (5-glutamine)α-melanotropin

    Biochemistry

    (1970)
  • J.G. Cannon et al.

    α-Melanocyte-stimulating hormone inhibits immunostimulatory and inflammatory action of interleukin-1

    J. Immunol.

    (1986)
  • Cited by (79)

    • Anterior Pituitary and Pars Intermedia Space

      2020, Hormonal Signaling in Biology and Medicine: Comprehensive Modern Endocrinology
    • Anterior Pituitary and Pars Intermedia Space: Corticotrophs (ACTH) and Melanotrophs (α-MSH)

      2019, Hormonal Signaling in Biology and Medicine: Comprehensive Modern Endocrinology
    • Key amino acid residue in Melanocortin-1 receptor (melanocyte α-MSH receptor) for ligand selectivity

      2017, Molecular and Cellular Endocrinology
      Citation Excerpt :

      Phe-Arg-Trp in MSH is identified to play an important role in ligand binding and signaling at MCRs (Yang et al., 2000; Haskell-Luevano et al., 1997b; Chen et al., 2006). When Phe, Arg and Trp in MSH were substituted with alanine, the ligand binding affinities and potencies were significantly decreased for these receptors (Grieco et al., 2002; Sahm et al., 1994; Bednarek et al., 1999). Substitution of Phe in position 7 of α-MSH with a DPhe (NDP-α-MSH) significantly increases ligand binding affinity and potency at MC1R, MC3R, MC4R and MC5R.

    • Bench-top to clinical therapies: A review of melanocortin ligands from 1954 to 2016

      2017, Biochimica et Biophysica Acta - Molecular Basis of Disease
      Citation Excerpt :

      The full length peptide possesses nonselective sub-nanomolar to nanomolar potencies at the MC1R, MC3R, MC4R, and MC5R [46,47]. Alanine scans of α-MSH have also indicated the importance of the Met4, Phe7, Arg8, and Trp9 positions for binding and functional activity at the mouse MC1R and rat MC3R [48,49]. A 2016 report examining the cloned mouse receptors indicated that in addition to positions Met4, Phe7, Arg8, and Trp9, the Glu5 and His6 positions also affect functional activity [47].

    View all citing articles on Scopus
    1

    Present address: Department of Pharmacy, University of Brighton, Cockcroft Building, Moulsecoomb, Brighton, BN2 4GJ, UK.

    View full text