Abstract
Bradykinin-related peptides (BRPs) family is one of the most significant myotropic peptide families derived from frog skin secretions. Here, a novel BRP callitide was isolated and identified from the red-eyed leaf frog, Agalychnis callidryas, with atypical primary structure FRPAILVRPK-NH2. The mature peptide was cleaved N-terminally at a classic propeptide convertase cleavage site (-KR-) and at the C-terminus an unusual -GKGKGK sequence was removed using the first G residue as an amide donor for the C-terminally-located K residue. Thereafter, the synthetic replicates of callitide were assessed the myotropic activity and showed a significant contraction of balder, with the 0.63 nM EC50 value, more potent than most discovered myotropic peptides. The binding mode was further speculated by molecular docking and stimulation. The result indicated that the C-terminal of callitide might selectively bind to bradykinin receptor B2 (BKRB2). Further investigation of the callitide needs to be done in the future to be exploited as potential future drug leads.
Highlights
The biosynthetic compounds from amphibian skin have attracted considerable attention for many decades and currently, are undergoing a renaissance in interest as chemical drugs fail and new diseases emergence [1]
A single transcript encoding the callitide biosynthetic precursor was consistently cloned from the constructed cDNA library of Agalychnis callidryas
The novel peptide was named callitide, and the biosynthetic precursor-encoding cDNA has submitted to the National Center for Biotechnological Information (NCBI) database
Summary
The biosynthetic compounds from amphibian skin have attracted considerable attention for many decades and currently, are undergoing a renaissance in interest as chemical drugs fail and new diseases emergence [1]. The bioactive peptides have attracted specific interest due to their potent activities and abundance. The myotropic peptides are significant endogenous peptides in amphibian skin, including bradykinin (BK), bombesin, tachykinin (TK), tryptophyllin (TPH), caerulein, and cholecystokinin (CCK). BKs and BK-related peptides active mammalian BKs, which affect smooth muscle contraction, hypotension, vasodilation, pain, and inflammation. Following the first isolated BK, more than 70 BK-like peptides have further been discovered [2]. Many BK and BK-related peptides, which have identified from anuran species, were isolated from the family Bombinatatoridae, Hylidae, and Ranidae [3,4,5].
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