Wheat peptides reduce oxidative stress and inhibit NO production through modulating µ-opioid receptor in a rat NSAID-induced stomach damage model.

Non-steroidal anti-inflammatory drugs (NSAIDs) induce tissue damage and oxidative stress in animal models of stomach damage. In the present study, the protective effects of wheat peptides were evaluated in a NSAID-induced stomach damage model in rats. Different doses of wheat peptides or distilled water were administered daily by gavage for 30 days before the rat stomach damage model was established by administration of NSAIDs (aspirin and indomethacin) into the digestive tract twice. The treatment of wheat peptides decreased the NSAID-induced gastric epithelial cell degeneration and oxidative stress and NO levels in the rats. Wheat peptides significantly increased the superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities and decreased iNOS activity in stomach. The mRNA expression level of µ-opioid receptor was significantly decreased in wheat peptides-treated rats than that in in the control rats. The results suggest that NSAID drugs induced stomach damage in rats, wchih can be prevented by wheat peptides. The mechanisms for the protective effects were most likely through reducing NSAID-induced oxidative stress.

Synthesis of lipidated eNOS peptides by combining enzymatic, noble metal- and acid-mediated protecting group techniques with solid phase peptide synthesis and fragment condensation in solution.

Lipid-modified proteins play decisive roles in important biological processes such as signal transduction, organization of the cytoskeleton, and vesicular transport. Lipidated peptides embodying the characteristic partial structures of their parent lipidated proteins and semisynthetic proteins synthesized from such peptides are valuable tools for the study of these biological phenomena. We have developed an efficient synthesis strategy that allows for the synthesis of long multiply lipidated peptides embodying various side chain functional groups. The strategy was successfully applied in the synthesis of the N-terminal undetrigintapeptide of endothelial NO-synthase and related lipopeptides. Key elements of the synthesis strategy are the combined use of the enzyme-labile para-phenylacetoxybenzyloxycarbonyl (PhAcOZ) urethane as N-terminal blocking group, the Pd0-sensitive allyl ester as C-terminal protecting function and acid-labile side chain protecting groups for solution-phase synthesis of labile S-palmitoylated building blocks under the mildest conditions with solid-phase techniques and solution-phase fragment condensations. The successful synthesis of the triply lipidated 29-mer eNOS peptide convincingly demonstrates the full capacity of the protecting group methods.

The calmodulin-binding domain of the inducible (macrophage) nitric oxide synthase.

A domain in the inducible, macrophage nitric oxide (NO) synthase has been selected as the putative calmodulin-binding site. The domain was synthesized as a peptide of 29 residues [P29, NO synthase-(504-532)-peptide], having the accepted hydrophobic/basic composition of calmodulin-binding domains and containing, like most of them, an aromatic amino acid at its N-terminus and a long chain aliphatic residue 12 amino acids downstream of it. A 34-residue peptide from the synthase sequence [P34, NO synthase-(499-532)-peptide], consisting of peptide P29 and of the five extra N-terminal amino acids, three of them basic, was also synthesized. Both peptides bound calmodulin in the presence as well as in the absence of Ca2+ (i.e. in the presence of excess EGTA). The KD of the binding in the presence of Ca2+ was < or = 1 nM. The binding affinity was lower, but still remarkably high in the presence of EGTA. The peptides counteracted the stimulation by calmodulin of a classical calmodulin-target enzyme, the Ca2+ pump of the plasma membrane.