Cis and trans proline conformers are often associated with dramatic changes in the biological function of peptides. A slow equilibrium between cis and trans Ile-Pro amide bond conformers occurs in constrained derivatives of the native marine cyclic heptapeptide stylostatin 1 (cyclo-(NSLAIPF)), a potential anticancer agent. In this work, four cyclopeptides, cyclo-(NSTAIPF), cyclo-(KSTAIPF), cycl...

Because angiogenesis plays a major role in the perpetuation of inflammatory arthritis, we explored a method for selectively targeting and destroying new synovial blood vessels. Mice with collagen-induced arthritis were injected intravenously with phage expressing an RGD motif. In addition, the RGD peptide (RGD-4C) was covalently linked to a proapoptotic heptapeptide dimer, D(KLAKLAK)2, and was ...

Activated charcoal (SuperChar) has been recommended for therapeutic use against poisoning by several toxic agents, but it has not been tested against microcystin-LR toxicosis. Microcystin-LR, a cyclic heptapeptide isolated from fresh water blue-green algae, has been shown to be a potent hepatotoxin in animals and in man. Studies were performed to determine the degree of in vitro adsorption of m...

Microcystin-FR a cyclic heptapeptide was isolated from Nostoc spongiaeforme and purified by thin layer chromatography, MALDI TOFF Ms and HPLC methods. The Swiss albino mice dosed with the sub lethal concentration of 0.8μg/kg body weight of microcystin-FR were subjected to a battery of behavioural depression models such as tail suspension test (TST), force swim test (FST) and elevated plus maze ...

Amatoxins, the lethal constituents of poisonous mushrooms in the genus Amanita, are bicyclic octapeptides. Two genes in A. bisporigera, AMA1 and PHA1, directly encode alpha-amanitin, an amatoxin, and the related bicyclic heptapeptide phallacidin, a phallotoxin, indicating that these compounds are synthesized on ribosomes and not by nonribosomal peptide synthetases. alpha-Amanitin and phallacidi...

The protein serine/threonine phosphatases constitute a unique class of enzymes that are critical regulatory enzymes as they must counteract the activities of thousands of protein kinases in human cells. Uncontrolled inhibition of phosphatase activity by toxic inhibitors can lead to widespread catastrophic effects. Over the past decade, a number of natural product toxins have been identified whi...

We here demonstrated that the Soh1/MED31 protein is a stable component of Mediator complex isolated from Schizosaccharomyces pombe and Saccharomyces cerevisiae. Bioinformatic analysis traces the Soh1/MED31 family of Mediator subunits to the point of major eukaryotic divergence, before the appearance of the canonical heptapeptide repeat structure of the RNA polymerase II C-terminal domain.