RESUMO
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.
Assuntos
Hormônios Hipotalâmicos , Melaninas/metabolismo , Hormônios Hipofisários/metabolismo , Sequência de Aminoácidos , Animais , Quimotripsina , Estabilidade de Medicamentos , Peixes , Técnicas In Vitro , Melaninas/antagonistas & inibidores , Melaninas/química , Dados de Sequência Molecular , Fragmentos de Peptídeos/antagonistas & inibidores , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/metabolismo , Hormônios Hipofisários/antagonistas & inibidores , Hormônios Hipofisários/química , TripsinaRESUMO
Paracoccidioidomycosis (South American blastomycosis) is a severe deep mycosis that begins in the lungs, mouth and pharynx and can affect the whole organism through lymphatic and hematologic dissemination. It is caused by the fungus Paracoccidioides brasiliensis and occurs in warm and humid regions near large forest. The sulfonamides are very active and represent the therapy of choice. Special cases are treated with Amphotericin B.