Caeruleins

Abstract

Caerulein [pEQDY(SO3H)TGWMDF-NH2] is a common host-defense peptide of tree frogs of the genus Litoria, which has also been identified in several other frog genera. Caerulein is a hypertensive and smooth muscle active peptide that shows gastrin-like bioactivity similar to that of cholecystokinin 8 (CCCK-8), namely, smooth muscle activity, reduction of blood pressure, together with modification of satiety, sedation, and thermoregulation. Many modified caerulein-type peptides also occur in tree frogs, while some of these, Litoria splendida, Litoria rothii, and Litoria peronii change their caerulein content seasonally. The preprocaerulein sequence from L. peronii is different from those of other active skin peptides from tree frogs of the genus Litoria, suggesting that the ancestral gene producing caerulein is different from that producing other active peptides from Litoria.