Enzymological studies of melanin concentrating hormone (MCH) and related analogues.
1. Salmon melanin concentrating hormone (MCH) is a cyclic heptadecapeptide possessing the following primary structure: Asp-Thr-Met-Arg-Cys-Met-Val-Gly-Arg-Val-Tyr-Arg-Pro-Cys-Trp-Glu-Val. 2. In the fish, Synbranchus marmoratus, skin bioassay MCH5-15 is equipotent to MCH whereas MCH5-14, which comprises only the ring structure, is about 100-fold less active. 3. MCH and two fragment analogues, MCH5-15 and MCH5-14, were studied to determine their relative stability in the presence of fish serum and purified proteolytic enzymes, trypsin and alpha-chymotrypsin. 4. After 4 hr incubation in fish serum, MCH5-15 retained 1/100, MCH5-14 1/1000 and MCH only 6/1000 of the potency of the native hormone. 5. The three peptides were also very resistant to degradation by purified proteolytic enzymes involving the following relative order of resistance: MCH5-14 > MCH5-15 > MCH. MCH5-14 potency was not altered after a 1 hr incubation in either enzyme whereas MCH retained 1/10 and 4/100 of its original potency, and MCH5-15 retained 1/10 and 8/10 of its original potency, after 1 hr in trypsin and alpha-chymotrypsin, respectively.
Castrucci
A M
AM
Departamento de Fisiologia Geral, Instituto de Biociências, Universidade de São Paulo, Brasil.
Visconti
M A
MA
Matsunaga
T O
TO
Hadley
M E
ME
Hruby
V J
VJ
D000595:Amino Acid Sequence; D000818:Animals; D002918:Chymotrypsin; D004355:Drug Stability; D005399:Fishes; D007028:Hypothalamic Hormones; D066298:In Vitro Techniques; D008543:Melanins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D010907:Pituitary Hormones / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D014357:Trypsin
D007028:Hypothalamic Hormones; D008543:Melanins; D010446:Peptide Fragments; D010907:Pituitary Hormones; C019463:melanin-concentrating hormone; D002918:Chymotrypsin; D014357:Trypsin