The production of toxin from bloom, scum or mat forming cyanobacteria in fresh, brackish and marine waters is becoming a global issue. The toxins produced comprise mainly hepatotoxins and neurotoxins. Of these toxins microcystin is a cyclic heptapeptide produced by Microcystis, Planktothrix, Anabaena, Nostoc, Hapalosiphon and Anabaenopsis. Microcystins (MCs) comprise more than 80 variants and a...

Bacillus subtilis JW-1 was isolated from rhizosphere soil as a potential biocontrol agent of bacterial wilt caused by Ralstonia solanacearum. Seed treatment followed by a soil drench application with this strain resulted in >80% reduction in bacterial wilt disease compared with that in the untreated control under greenhouse conditions. The antibacterial compound produced by strain JW-1 was puri...

A natural cyclic heptapeptide segetalin D [VIII] was synthesized by coupling of tripeptide unit Boc-Pro-Gly-Leu-OMe [V] with tetrapeptide unit Boc-Ser-Phe-Ala-Phe-OMe [VI] after proper deprotection at carboxyl and amino ends followed by cyclization of linear peptide segment. Structure of VIII was confirmed by spectral and elemental analyses. The newly synthesized cyclopeptide was tested for its...

Microcystins (MCs) are cyclic heptapeptide toxins and can accumulate in the liver. Cytochrome P450s (CYPs) play an important role in the biotransformation of endogenous substances and xenobiotics in animals. It is unclear if the CYPs are affected by MCs exposure. The objective of this study was to evaluate the effects of microcystin-LR (MCLR) on cytochrome P450 isozymes (CYP1A1, CYP2E1, and CYP...

Interference with fat hydrolysis results in the reduced use of ingested lipids. Inhibition of pancreatic lipase reduces the efficiency of fat absorption in the small intestine and thereby initiates modest long-term reduction in body weight. In an attempt to select peptides with affinity for the surface of pancreatic lipase and potential inhibitory activity, a random, cyclic heptapeptide phage-d...

The positive transcription elongation factor b (P-TEFb) contains cyclin T1 (CycT1) and cyclin-dependent kinase 9 (Cdk9). For activating the expression of eukaryotic genes, the histidine-rich sequence in CycT1 binds the heptapeptide repeats in the C-terminal domain (CTD) of RNA polymerase II (RNAPII), whereupon Cdk9 phosphorylates the CTD. We found that alanine-substituted heptapeptide repeats t...

The direct peptide reactivity assay (DPRA) is a validated method for in vitro assessment of the skin sensitization potential of chemicals. In the present work, we describe a peptide reactivity assay using 96-well plate format and systematically identified the optimal assay conditions for accurate and reproducible classification of chemicals with known sensitizing capacity. The aim of the resear...

Angiotensin (Ang)-(1-7) has cardiovascular protective effects and is the opponent of the often detrimental Ang II within the renin-angiotensin system. Although it is well accepted that the G-protein-coupled receptor Mas is a receptor for the heptapeptide, the lack in knowing initial signaling molecules stimulated by Ang-(1-7) prevented definitive characterization of ligand/receptor pharmacology...