Differentiation of the structural features of melanotropins important for biological potency and prolonged activity in vitro

B. C. Wilkes, T. K. Sawyer, Victor J Hruby, M. E. Hadley

Research output: Contribution to journalArticle

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Abstract

Several α-melanotropin (α-MSH) analogues have been synthesized and tested for their melanotropin activities in order to determine the functional importance of certain amino acids near the primary active sequence of α-MSH, H-(Glu)-His-Phe-Arg-Trp-Gly-OH, on the biological activities of the hormone. In particular, we have examined the importance of the 4 and 11 positions in conjunction with the substitution of L-Phe in position 7 by D-Phe on potency amd prolonged activity of the hormone. In the frog (Rana pipiens) skin system the relative potencies were found to be: [Nle4, D-Phe7]-α-MSH (60) > α-MSH (1.0) > Ac-[NLE4, D-Phe7]-α-MSH4-11-NH2 (0.16) > Ac-[Nle4, D-Phe7]-α-MSH4-10-NH2 (0.02) ~ Ac-[D-Phe7]-α-MSH5-11-NH2 (0.01) > Ac-[Nle4}-α-MSH4-10-NH2 (0.002) = Ac-[Nle4]-α-MSH4-11-NH2 > Ac-α-MSH4-10-NH2 (0.0003) ≥ Ac-α-MSH5-11-NH2 (0.0002). On the other hand the relative potencies on the lizard (Anolis carolinensis) skin system were found to be: Ac-[Nle4, D-Phe7]-α-MSH4-10-NH2 (10) ≥ Ac-[Nle4, D-Phe7]-α-MSH4-11-NH2 (8.0) ≥ Ac-[Nle4, D-Phe7]-α-MSH (5.0) > α-MSH (1.0) = Ac-[Nle4]-α-MSH4-11-NH2 = Ac [D-Phe7]-α-MSH5-11-NH2 > Ac [Nle4]-α-MSH4-10-NH2 (0.06) > Ac-α-MSH5-11-NH2 (0.01) > Ac-α-MSH4-10-NH2 (0.004). Detailed analyses of these data suggest species-dependent differences in the stereostructural relationships of the residues in the 4, 7, and 11 positions for melanotropic potency in vitro. Particularly noteworthy is the observation that the 4-11 fragment analogue Ac-[Nle4}-α-MSH4-11-NH2 is equipotent to α-MSH in the lizard assay system, suggesting that the 1-3, 12, and 13 residues of α-MSH are not involved in the binding or transduction in this system. Examination of the ability of these α-melanotropin analogues to effect sustained biological activity (prolongation) following removal of exogenous peptide from the bioassay medium showed striking differences in the two systems. On the lizard skin assay, only [Nle4, D-Phe7]-α-MSH, Ac-[Nle4, D-Phe7]-α-MSH4-11-NH2 and Ac-[Nle4, D-Phe7]-α-MSH4-10-NH2 effect marked prolonged melanotropic activity as compared to α-MSH. In contrast, on the frog skin assay, only [Nle4, D-Phe7]-α-MSH, Ac-[Nle4, D-Phe7]-α-MSH4-11-NH2, Ac-α-MSH5-11-NH2, and Ac-[Nle4]-α-MSH4-10-NH2 exhibited significant prolonged activity. These results demonstrate that relative potency and prolongation of melanotropic activity are not directly related, but rather are the manifestation of different, species-dependent structural and topographical requirements for peptide-receptor interactions related to binding and signal transduction.

Original languageEnglish (US)
Pages (from-to)313-324
Number of pages12
JournalInternational Journal of Peptide and Protein Research
Volume22
Issue number3
StatePublished - 1983

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Melanocyte-Stimulating Hormones
Lizards
Skin
Assays
Bioactivity
In Vitro Techniques
Anura
Hormones
Rana pipiens
Signal transduction
Peptide Receptors
Bioassay
Biological Assay

ASJC Scopus subject areas

  • Biochemistry

Cite this

Differentiation of the structural features of melanotropins important for biological potency and prolonged activity in vitro. / Wilkes, B. C.; Sawyer, T. K.; Hruby, Victor J; Hadley, M. E.

In: International Journal of Peptide and Protein Research, Vol. 22, No. 3, 1983, p. 313-324.

Research output: Contribution to journalArticle

@article{75e304fd6de04fedb02b907e2ad8a045,
title = "Differentiation of the structural features of melanotropins important for biological potency and prolonged activity in vitro",
abstract = "Several α-melanotropin (α-MSH) analogues have been synthesized and tested for their melanotropin activities in order to determine the functional importance of certain amino acids near the primary active sequence of α-MSH, H-(Glu)-His-Phe-Arg-Trp-Gly-OH, on the biological activities of the hormone. In particular, we have examined the importance of the 4 and 11 positions in conjunction with the substitution of L-Phe in position 7 by D-Phe on potency amd prolonged activity of the hormone. In the frog (Rana pipiens) skin system the relative potencies were found to be: [Nle4, D-Phe7]-α-MSH (60) > α-MSH (1.0) > Ac-[NLE4, D-Phe7]-α-MSH4-11-NH2 (0.16) > Ac-[Nle4, D-Phe7]-α-MSH4-10-NH2 (0.02) ~ Ac-[D-Phe7]-α-MSH5-11-NH2 (0.01) > Ac-[Nle4}-α-MSH4-10-NH2 (0.002) = Ac-[Nle4]-α-MSH4-11-NH2 > Ac-α-MSH4-10-NH2 (0.0003) ≥ Ac-α-MSH5-11-NH2 (0.0002). On the other hand the relative potencies on the lizard (Anolis carolinensis) skin system were found to be: Ac-[Nle4, D-Phe7]-α-MSH4-10-NH2 (10) ≥ Ac-[Nle4, D-Phe7]-α-MSH4-11-NH2 (8.0) ≥ Ac-[Nle4, D-Phe7]-α-MSH (5.0) > α-MSH (1.0) = Ac-[Nle4]-α-MSH4-11-NH2 = Ac [D-Phe7]-α-MSH5-11-NH2 > Ac [Nle4]-α-MSH4-10-NH2 (0.06) > Ac-α-MSH5-11-NH2 (0.01) > Ac-α-MSH4-10-NH2 (0.004). Detailed analyses of these data suggest species-dependent differences in the stereostructural relationships of the residues in the 4, 7, and 11 positions for melanotropic potency in vitro. Particularly noteworthy is the observation that the 4-11 fragment analogue Ac-[Nle4}-α-MSH4-11-NH2 is equipotent to α-MSH in the lizard assay system, suggesting that the 1-3, 12, and 13 residues of α-MSH are not involved in the binding or transduction in this system. Examination of the ability of these α-melanotropin analogues to effect sustained biological activity (prolongation) following removal of exogenous peptide from the bioassay medium showed striking differences in the two systems. On the lizard skin assay, only [Nle4, D-Phe7]-α-MSH, Ac-[Nle4, D-Phe7]-α-MSH4-11-NH2 and Ac-[Nle4, D-Phe7]-α-MSH4-10-NH2 effect marked prolonged melanotropic activity as compared to α-MSH. In contrast, on the frog skin assay, only [Nle4, D-Phe7]-α-MSH, Ac-[Nle4, D-Phe7]-α-MSH4-11-NH2, Ac-α-MSH5-11-NH2, and Ac-[Nle4]-α-MSH4-10-NH2 exhibited significant prolonged activity. These results demonstrate that relative potency and prolongation of melanotropic activity are not directly related, but rather are the manifestation of different, species-dependent structural and topographical requirements for peptide-receptor interactions related to binding and signal transduction.",
author = "Wilkes, {B. C.} and Sawyer, {T. K.} and Hruby, {Victor J} and Hadley, {M. E.}",
year = "1983",
language = "English (US)",
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journal = "International Journal of Peptide and Protein Research",
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TY - JOUR

T1 - Differentiation of the structural features of melanotropins important for biological potency and prolonged activity in vitro

AU - Wilkes, B. C.

AU - Sawyer, T. K.

AU - Hruby, Victor J

AU - Hadley, M. E.

PY - 1983

Y1 - 1983

N2 - Several α-melanotropin (α-MSH) analogues have been synthesized and tested for their melanotropin activities in order to determine the functional importance of certain amino acids near the primary active sequence of α-MSH, H-(Glu)-His-Phe-Arg-Trp-Gly-OH, on the biological activities of the hormone. In particular, we have examined the importance of the 4 and 11 positions in conjunction with the substitution of L-Phe in position 7 by D-Phe on potency amd prolonged activity of the hormone. In the frog (Rana pipiens) skin system the relative potencies were found to be: [Nle4, D-Phe7]-α-MSH (60) > α-MSH (1.0) > Ac-[NLE4, D-Phe7]-α-MSH4-11-NH2 (0.16) > Ac-[Nle4, D-Phe7]-α-MSH4-10-NH2 (0.02) ~ Ac-[D-Phe7]-α-MSH5-11-NH2 (0.01) > Ac-[Nle4}-α-MSH4-10-NH2 (0.002) = Ac-[Nle4]-α-MSH4-11-NH2 > Ac-α-MSH4-10-NH2 (0.0003) ≥ Ac-α-MSH5-11-NH2 (0.0002). On the other hand the relative potencies on the lizard (Anolis carolinensis) skin system were found to be: Ac-[Nle4, D-Phe7]-α-MSH4-10-NH2 (10) ≥ Ac-[Nle4, D-Phe7]-α-MSH4-11-NH2 (8.0) ≥ Ac-[Nle4, D-Phe7]-α-MSH (5.0) > α-MSH (1.0) = Ac-[Nle4]-α-MSH4-11-NH2 = Ac [D-Phe7]-α-MSH5-11-NH2 > Ac [Nle4]-α-MSH4-10-NH2 (0.06) > Ac-α-MSH5-11-NH2 (0.01) > Ac-α-MSH4-10-NH2 (0.004). Detailed analyses of these data suggest species-dependent differences in the stereostructural relationships of the residues in the 4, 7, and 11 positions for melanotropic potency in vitro. Particularly noteworthy is the observation that the 4-11 fragment analogue Ac-[Nle4}-α-MSH4-11-NH2 is equipotent to α-MSH in the lizard assay system, suggesting that the 1-3, 12, and 13 residues of α-MSH are not involved in the binding or transduction in this system. Examination of the ability of these α-melanotropin analogues to effect sustained biological activity (prolongation) following removal of exogenous peptide from the bioassay medium showed striking differences in the two systems. On the lizard skin assay, only [Nle4, D-Phe7]-α-MSH, Ac-[Nle4, D-Phe7]-α-MSH4-11-NH2 and Ac-[Nle4, D-Phe7]-α-MSH4-10-NH2 effect marked prolonged melanotropic activity as compared to α-MSH. In contrast, on the frog skin assay, only [Nle4, D-Phe7]-α-MSH, Ac-[Nle4, D-Phe7]-α-MSH4-11-NH2, Ac-α-MSH5-11-NH2, and Ac-[Nle4]-α-MSH4-10-NH2 exhibited significant prolonged activity. These results demonstrate that relative potency and prolongation of melanotropic activity are not directly related, but rather are the manifestation of different, species-dependent structural and topographical requirements for peptide-receptor interactions related to binding and signal transduction.

AB - Several α-melanotropin (α-MSH) analogues have been synthesized and tested for their melanotropin activities in order to determine the functional importance of certain amino acids near the primary active sequence of α-MSH, H-(Glu)-His-Phe-Arg-Trp-Gly-OH, on the biological activities of the hormone. In particular, we have examined the importance of the 4 and 11 positions in conjunction with the substitution of L-Phe in position 7 by D-Phe on potency amd prolonged activity of the hormone. In the frog (Rana pipiens) skin system the relative potencies were found to be: [Nle4, D-Phe7]-α-MSH (60) > α-MSH (1.0) > Ac-[NLE4, D-Phe7]-α-MSH4-11-NH2 (0.16) > Ac-[Nle4, D-Phe7]-α-MSH4-10-NH2 (0.02) ~ Ac-[D-Phe7]-α-MSH5-11-NH2 (0.01) > Ac-[Nle4}-α-MSH4-10-NH2 (0.002) = Ac-[Nle4]-α-MSH4-11-NH2 > Ac-α-MSH4-10-NH2 (0.0003) ≥ Ac-α-MSH5-11-NH2 (0.0002). On the other hand the relative potencies on the lizard (Anolis carolinensis) skin system were found to be: Ac-[Nle4, D-Phe7]-α-MSH4-10-NH2 (10) ≥ Ac-[Nle4, D-Phe7]-α-MSH4-11-NH2 (8.0) ≥ Ac-[Nle4, D-Phe7]-α-MSH (5.0) > α-MSH (1.0) = Ac-[Nle4]-α-MSH4-11-NH2 = Ac [D-Phe7]-α-MSH5-11-NH2 > Ac [Nle4]-α-MSH4-10-NH2 (0.06) > Ac-α-MSH5-11-NH2 (0.01) > Ac-α-MSH4-10-NH2 (0.004). Detailed analyses of these data suggest species-dependent differences in the stereostructural relationships of the residues in the 4, 7, and 11 positions for melanotropic potency in vitro. Particularly noteworthy is the observation that the 4-11 fragment analogue Ac-[Nle4}-α-MSH4-11-NH2 is equipotent to α-MSH in the lizard assay system, suggesting that the 1-3, 12, and 13 residues of α-MSH are not involved in the binding or transduction in this system. Examination of the ability of these α-melanotropin analogues to effect sustained biological activity (prolongation) following removal of exogenous peptide from the bioassay medium showed striking differences in the two systems. On the lizard skin assay, only [Nle4, D-Phe7]-α-MSH, Ac-[Nle4, D-Phe7]-α-MSH4-11-NH2 and Ac-[Nle4, D-Phe7]-α-MSH4-10-NH2 effect marked prolonged melanotropic activity as compared to α-MSH. In contrast, on the frog skin assay, only [Nle4, D-Phe7]-α-MSH, Ac-[Nle4, D-Phe7]-α-MSH4-11-NH2, Ac-α-MSH5-11-NH2, and Ac-[Nle4]-α-MSH4-10-NH2 exhibited significant prolonged activity. These results demonstrate that relative potency and prolongation of melanotropic activity are not directly related, but rather are the manifestation of different, species-dependent structural and topographical requirements for peptide-receptor interactions related to binding and signal transduction.

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EP - 324

JO - International Journal of Peptide and Protein Research

JF - International Journal of Peptide and Protein Research

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