Identification of LDL-receptor transcription stimulating peptides from soybean hydrolysate in human hepatocytes

Soybean protein and its hydrolysate have been reported to have cholesterol-lowering property, but the responsible components are still largely unknown. In previous study, we found that soybean protein hydrolysate (SPH) prepared with the protease from Bacillus amyloliquefaciens FSE-68, strongly stimulates transcription of low density lipoprotein receptor (LDL-R). To identify LDL-R transcription stimulating peptides in human hepatocytes, the SPH was fractionated with gel permeation chromatograpy and the active fraction was further separated by using reverse-phase chromatography. Several peptides in the most active fraction were identified by LC/MS and MS/MS analysis. LDL-R transcription stimulating peptides were synthesized on the basis of identified sequences, and their effect on LDL-R transcription was tested in vitro. Among the synthesized peptides, Phe-Val-Val-Asn-Ala-Thr-Ser-Asn (FVVNATSN) showed the strongest activity, and LDL-R transcription of hepatic cells was increased to 248.8% (compared to 100% of untreated control) by FVVNATSN at a concentration of 100 mu M. This study provides direct evidence that peptides derived from soybean protein can influence LDL-R transcription in hepatocytes.