Differential structural requirements for the MSH and MCH activities of melanin concentrating hormone.
H-Asp-Thr-Met-Arg-Cys-Met-Val-Gly-Arg-Val-Tyr-Arg-Pro-Cys-Trp-Glu-Val-OH , melanin concentrating hormone (MCH), exhibits both melanin granule concentrating and dispersing (MSH-like) activities. Fragment analogues of MCH were synthesized as described herein and the melanotropic activities of the peptides were determined. In the frog (Rana pipiens) and lizard (Anolis carolinensis) skin bioassays, the 5-17 and 5-14 fragments of MCH were inactive (at concentrations of 10(-5)M or less), whereas the 1-14 sequence exhibited minimal (about 10%) MSH-like activity compared to MCH, which, as reported previously, was about 600 times less active than alpha-MSH. In the teleost (fish) skin bioassay, the MCH5-17 analogue was equipotent to MCH, whereas the 1-14 analogue was 10-30 times and the cyclic N- and C- terminal truncated analogue, MCH5-14, was about 300 times less active than MCH. These results suggest that the N-terminal sequence is particularly critical to MSH-like activity in the tetrapod species studied, whereas other structural regions of MCH, particularly in the C-terminal, are more related to MCH activity in teleosts.
D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D007028:Hypothalamic Hormones; D008116:Lizards; D008543:Melanins / Q000502:physiology*; D010446:Peptide Fragments / Q000502:physiology; D010455:Peptides / Q000502:physiology*; D010907:Pituitary Hormones / Q000502:physiology*; D011894:Rana pipiens
D007028:Hypothalamic Hormones; D008543:Melanins; D010446:Peptide Fragments; D010455:Peptides; D010907:Pituitary Hormones; C019463:melanin-concentrating hormone; C027714:melanophore-dispersing hormone