Research On Purification And Characteristics Of Polypeptides From Urechis Unicinctus

The marine has special characters of high salt, high pressure, low temperature and little nutrition. Because of the different circumstances, the acid and protein in halobios are different from those in land living animals.So far most polypeptides purified from halobios have arisen extensive attention of researchers,which have the ability of antitumor and antigerm. Based on the results above, a kind of polypeptides from the haemocoelomic fluid of Urechis unicinctus is purified and its bioacitivity is examined.The crude polypeptides is purified through filtration and sephadex G-25, sephacryl S-100, CM-sephadex gel chromatography. By means of SDS-PAGE, it is found that the polypeptide's molecular weight is among 6KD, and the recover rate of protein was 31.7%.The antitumorous activity and the influence in normal cells are examined through cell culturation in vitro.The viability is examined with MTT assay.In conclusion, it is found that the polypeptides has the ability of antitumor to hepatoma, Hela and S180 tumor cell ,and it has the most distinct effect on hepatoma, inhibitory rate of which comes to 80% when polypeptide's concentration is 500μg/ml, while the inhibitory rate to Hela and S180 tumor cell with the same concentration are 37.5% and 19.8% .The effection to normal liver cell is also examined using the same method ,and it is indicated that the polypeptides purified from Urechis unicinctus has little effection to normal liver cell.The peptides is ig administered to Sarcoma 180 mice,the inhibitory rate is calculated .From the conclusion ,it is indicated the polypeptides could inhibit tumor growth ,and with increase of the concentration, the inhibitory rate strengthens.When the dosage is 750mg/kg, inhitory rate could reach 31.9%,which has distinct difference with comparison.The polypeptides is also ig administered to KM mice which is used to examine the effect on mice immune system in vivo.Different groups are given diverse polypeptides dosages .20 days later, main immunity indexes are calculated.The data show that the polypeptides has significant effect on immune function in vivo.The experimenal mouse administrated peptides at different doses could increase clearance rate of carbon particles, promote the ability of PMФphagocytosis as well as IL-1 multiplication from PMФ, enhance the weight index of thymus and spleen, and increase the multiplicable ability of spleen lymphocyte.The increasing effect of polypeptides is dose-indepently in this study and the best effect is shown at 750 mg/kg bw(P<0.05).From above immune indexes it is found that the polypeptides purified from the haemocoelomic fluid of Urechis unicinctus exhibits favorable effects on immune functions in vivo.In conclusion, the results above prove that the polypeptides from the haemocoelomic fluid of Urechis unicinctus possesses inmunostimulating effects on mice immune function and also has the effect on inhibition to tumor growth.This study provides foundation for the biological properties of the polypeptides from the haemocoelomic fluid of Urechis unicinctus and expands wide application of the polypeptides in healthy care.