The structures of four bombesins and their cloned precursor-encoding cDNAs from acid-solvated skin secretion of the European yellow-bellied toad, Bombina variegata

Four different bombesins (bombesin, His(6)-bombesin, Phe(13)-bombesin and Asp(2)-, Phe(4)-SAP-bombesin) have been identified by a systematic sequencing study of peptides in reverse phase HPLC fractions of the skin secretion of the European yellow-bellied toad, Bombina variegata, that had been solvated in 0.1% (v/v) aqueous trifluoroacetic acid (TFA) and stored frozen at -20°C for 12 years. By using a 3'- and 5'-RACE PCR strategy, the corresponding biosynthetic precursor-encoding cDNAs of all four peptides were cloned from a cDNA library made from the same long-term frozen, acid-solvated skin secretion sample following thawing and lyophilization. Canonical bombesin and His(6)-bombesin are classical bombesin sub-family members, whereas Phe(13)-bombesin and Asp(2)-, Phe(4)-SAP-bombesin, belong to the litorin/ranatensin sub-family of bombesin-like peptides (BLPs). Assignment of these peptides to respective sub-families, was based upon both their primary structural similarities and their comparative pharmacological activities. An interesting observation in this study, was that the nucleotide sequences of the open-reading frames of cloned cDNAs encoding bombesin and its His(6)-substituted analog, were identical except for a single base that was responsible for the change observed at the position 6 residue in the mature peptide from Asn to His. In contrast, the precursor cDNA nucleotide sequences encoding the Phe(13)-bombesins, exhibited 53 base differences. The pharmacological activities of synthetic replicates of each bombesin were compared using two different mammalian smooth muscle preparations and all four peptides were found to be active. However, there were significant differences in their relative potencies.

DPP IV resistance and insulin releasing activity of a novel di-substituted analogue of glucose-dependent insulinotropic polypeptide, (Ser(2)-Asp(13))GIP

Structure-function studies suggest that preservation of the N-terminus and secondary structure of glucose-dependent insulinotropic polypeptide (GIP) is important for biological activity. Therefore, a novel di-substituted analogue of GIP, (Ser(2)-Asp(13))GIP, containing a negatively charged Asp residue in place of an Ala in position 13, seas synthesised and evaluated for in vitro biological activity. Incubation with dipeptidyl peptidase IV (DPP IV) showed the half-lives of GIP and (Ser(2)-Asp(13))GIP to be 2.3 and >4 h, respectively. Insulin releasing studies in clonal pancreatic BRIN-BD11 cells demonstrated that (Ser(2)-Asp(13))GIP (10(-12) to 10(-7) mol/l) was significantly less potent (60-90%; P

Relationship between G894T polymorphism (Glu 298 Asp variant) in endothelial nitric oxide synthase and nitric oxide mediated endothelial function in human atherosclerosis.

Nitric oxide (NO), produced by endothelial nitric oxide synthase (eNOS), plays important roles in normal vascular homeostasis, and reduced endothelial NO bioactivity is an important feature of vascular disease states. The Glu298Asp (G894T) polymorphic variant of eNOS has been associated with vascular disease, but functional data are lacking. Accordingly, we examined the relationships between NO-mediated endothelial function, the presence of the eNOS Glu298Asp variant, and clinical risk factors for atherosclerosis. Endothelium-dependent vasorelaxations to different agonists were determined in human saphenous veins obtained from patients with coronary artery disease and identified risk factors (n = 104). Patients were genotyped for the eNOS G894T polymorphism. Nitric oxide-mediated endothelial vasorelaxations were highly variable between patients. Reduced vasorelaxations were associated with increased number of clinical risk factors for atherosclerosis (r = - 0.54, P