Isolation and characterization of four novel bioactive peptides from a polychaete annelid, Perinereis vancaurica

Preparation of Nereid oligopeptide and investigation of the mechanism underlying the induction of apoptosis in human lung cancer H1299 cells

In the present study, oligopeptides from Nereid (Perinereis aibuhitensis) were prepared via enzymatic hydrolysis, and the mechanism underlying the induction of apoptosis in H1299 cells was investigated. According to the analysis of the inhibition rate on proliferation, alkaline protease demonstrated the best enzymatic efficiency. The optimal conditions for hydrolysis were as follows: 50°C and pH 10 for 6 h; a material-to-liquid ratio of 1:1 (g/ml); and addition of 400 U/g enzyme. The hydrolysates were purified using ultrafiltration, anion chromatography, gel filtration chromatography, and high-performance liquid chromatography. The Nereid oligopeptide (NOP), with a molecular weight of 841 kDa and an amino acid sequence of glutamine-isoleucine-asparagine-glutamine-histidine-leucine, was obtained. NOP inhibited the proliferation of H1299 cells in a time- and dose-dependent manner. Morphological changes and apoptosis were also induced by NOP in H1299 cells. The western blot analysis revealed that the B-cell lymphoma 2/Bcl-2 associated X (Bcl-2/Bax) ratio was reduced by 24.7% in the NOP treatment group compared with the control group. The relative expression levels of cleaved caspase-9 (cleaved-CASP9) and cleaved caspase-3 (cleaved-CASP3) in the NOP treatment group were 2.55- and 1.71-fold higher than those measured in the control group, respectively. These results suggested that NOP exerts antitumor effects by influencing the proliferation and apoptosis of H1299 cells.

Thelepamide: an unprecedented ketide-amino acid from Thelepus crispus, a marine annelid worm

Thelepamide (1) was characterized during a program to study cytotoxic substances from an unusual source, the tidal zone-derived annelid Thelephus crispus. Its structure contains a tetraketide and a tripeptide subunit and possesses striking atom diversity, consisting of 17 carbons and 8 heteroatoms. The relative configurations at four chiral sites were elucidated via ROESY, J-based configurational analysis, and DFT calculations. It was modestly active against leukemia cells (IC50 = 5 μg/mL) and inactive against solid tumor cell lines.

Purification and properties of the protease from Perinereis aibuhitensis Grube

AIM: To purify a new protease from the clamworm Perinereis aibuhitensis Grube, and study its properties.

METHODS: After homogenization, Superdex-75 chromatography, MonoQ^TM chromatography, and SP-Sepharose 4B chromatography were used ordinally to purify the protease from the clamworm Perinereis aibuhitensis Grube. A new gelatin zymography method was used to study the proteolytic activity of the protease: protease separated by non-reductive SDS-PAGE was electrophoretically transferred to a gel containing gelatin, and the proteolytic activity of the protease was determined by the clear zone of the electrophoretic protein band. The effect of pH value, temperature, protease inhibitor, organic solvents and metal ions on the proteolytic activity of the protease was studied.

RESULTS: After purification, one kind of protease was obtained, which showed two protein bands with molecular weights of 34900 and 33900 separately by reductive SDS-PAGE, while three bands with molecular weights of 65600, 57900, and 43500 separately by non-reductive SDS-PAGE. Gelatin zymography showed that the proteolytic activity mainly appeared around the band of M_r 66000. The protease was stable and displayed high proteolytic activity within the range of pH 8 to 10 and at 20-35 ℃ It was strongly inhibited by phenylmethyl sulfonyl fluoride (PMSF), while stable in the presence of organic solvents.

CONCLUSION: The protease is composed of two subunits, whose molecular weights are 33900 and 34900, respectively. Gelatin zymography is sensitive and effective in studying the proteolytic activity of proteases.

A novel GGNG-related neuropeptide from the polychaete Perinereis vancaurica

The GGNG peptides are myoactive peptides so far identified from earthworms and leeches, which are the earthworm excitatory peptides (EEP) and the leech excitatory peptide (LEP), respectively. A novel GGNG peptide was isolated and structurally determined from a marine polychaete, Perinereis vancaurica, using a combination of immunological assay and high performance liquid chromatography (HPLC). The peptide was a pentadecapeptide whose amino acid sequence was similar to that of EEP and LEP, and showed myoactivity on isolated esophagus of P. vancaurica with a threshold concentration of 10(-10)M. The peptide was designated as polychaete excitatory peptide (PEP). Amidation of the alpha-carboxyl group of C-terminal residue occurred in PEP. This is the case for LEP, but not for EEP. The cDNA cloning revealed that the structure of the PEP precursor is more similar to the EEP precursor than to the LEP precursor. Immunohistochemical staining showed the presence of PEP in several neurons of central nervous system (CNS) as somata and neuropile structure, epithelial cells of the pharynx and epidermal cells throughout the body wall. Altogether these results support the physiological significance of PEP in regulation of the CNS neural activity and the peripheral myoactivity.