Glycopeptides In Soy Protein Hydrolysates And Their Effects On Proliferation Of Murine Splenocytes

Soy peptides have been one of focuses in the research and utility of protein since 1970s. Studies showed that soy peptides have many biological functions, such as hypocholesterol activity, antioxidativity, hypotensive activity, control of obesity and fatigue and so on. But there is no report about the biological activity of soy glycopeptides. The objective of the study was to obtain soy glycopeptides from -conglycinin hydrolydates and to confirm effects of glycopeptides on the proliferation of murine splenocytes by the method of cell incubation in vitro. In addition, the role of carbohydrate chains in the effect was also investigated.Alcalase and Pronase E were used to hydrolyze -conglycinin to prepare soy peptides. After isolated from soy peptides by Sephadex G-25, carbohydrate-containing peptides were pooled, and identified the carbohydrate-peptide linkage by thin-layer chromatography. Soy glycopeptides were treated with N-Glycosidase F and then applied to Sephadex G-25 to obtain peptides without carbohydrate. MTS/PMS colorimetric assay was used to determine the proliferation of murine splenocytes, in which absorbance at 492nm was consistent with the number of cells.In the study two kinds of soy glycopeptides were isolated from hydrolysates, with average molecular weight of 1670Da and 1135Da. The carbohydrate content of two glycopeptides was 8.23% and 9.66% respectively. Both of soy glycopeptides had inhibitory effects on ConA-stimulated proliferation of murine splenocytes. The degree of inhibitory effect on ConA-stimulated activity reached to 40%~50% at concentration ranging from 50~100pg/ml. When carbohydrate chains in glycopeptides were removed with N-Glycosidase F, the inhibitory effect of glycopeptide derived from Alcalase hydrolysate decreased, but that of glycopeptide from Pronase E hydrolysate changed little. On the other hand, both of glycopeptides showed promoting effects on proliferation of murine splenocytes in the absence of ConA. The results showed that soy glycopeptides have immunomodulatory effect from two aspects.