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Skin secretion of the toad Bombina variegata contains multiple insulin-releasing peptides including bombesin and entirely novel insulinotropic structures

Biomedical Sciences Research Institute Computer Science Research Institute Environmental Sciences Research Institute Nanotechnology & Advanced Materials Research Institute

Marenah, L, Flatt, Peter, Orr, DF, McClean, Stephen, Shaw, C and Abdel-Wahab, Yasser (2004) Skin secretion of the toad Bombina variegata contains multiple insulin-releasing peptides including bombesin and entirely novel insulinotropic structures. BIOLOGICAL CHEMISTRY, 385 (3-4). pp. 315-321. [Journal article]

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Abstract

Skin secretions of the toad Bombina variegata were evaluated for the isolation and characterisation of insulinotropic peptides. Crude secretions obtained from young adult toads by mild electrical stimulation of the dorsal skin surface were purified by reverse phase HPLC yielding 44 peaks. In acute incubations with glucoseresponsive BRINBD11 cells, peaks 21, 22, 23, 24 and 25 showed a 1.5-3.5-fold increase in insulin release compared with 5.6 mM glucose alone (p<0.001; n=3). Structural analyses of the purified insulinreleasing peaks were performed by automated Edman degradation and mass spectrometry. Peptides represented by peaks 21, 22 and 23 had molecular masses of 1641.7 Da, 1662.6 Da and 1619.8 Da respectively. These peptides were unblocked by removal of pyroglutamic acid from the Nterminus prior to Edman degradation, revealing lengths of 14 amino acids. Peak 21 yielded a primary structure of PyrQRLGHQWAVGHLM, which a data base search revealed as an analogue of bombesin (His6 bombesin), while peak 23 was an exact match of bombesin (PyrQRLGNQWAVGHLM) originally isolated from Bombina bombina. Peak 22 indicated a primary structure of PyrDSFGNQWARGHFM (72% homology with bombesin). Peaks 24 and 25 revealed entirely novel insulinotropic peptides with molecular masses and primary structures of 1650.5 Da and 2300.0 Da and GKPFYPPPIYPEDM (GM-14) and IYNAICPCKHCNKCKPGLLAN (IN-21) respectively. Preliminary studies on the mechanisms underlying the insulinotropic actions of peaks 21, 22, 23 and 24 suggest possible involvement of a cAMPdependent, G proteininsensitive pathway. These data indicate that Bombina variegata skin secretions contain peptides with insulinreleasing activity, which may have mammalian counterparts and prove useful for possible exploitation as antidiabetic agents from natural resources.

Item Type:Journal article
Faculties and Schools:Faculty of Life and Health Sciences
Faculty of Life and Health Sciences > School of Biomedical Sciences
Research Institutes and Groups:Biomedical Sciences Research Institute
Biomedical Sciences Research Institute > Diabetes
ID Code:3024
Deposited By:Professor Peter Flatt
Deposited On:14 Jan 2010 15:40
Last Modified:11 Jun 2010 11:18

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