Characterization of Lunasin Isolated from Soybean

Abstract

Lunasin is a novel and promising chemopreventive peptide from soybean. We have shown previously that lunasin suppresses transformation of mammalian cells caused by chemical carcinogens and inhibits skin carcinogenesis in mice when applied topically. Although the lunasin gene was cloned from soybean, all experiments carried out so far in our lab have used synthetic lunasin and therefore there is no detailed description of natural lunasin isolated from soybean. We report here the first characterization of soybean lunasin that includes definitive identification by mass peptide mapping, partial purification, and measurement of bioactivities of the various purified fractions and protein expression in the developing seed. The identity of lunasin in the seed extracts was established by Western blot analysis and mass spectrometric peptide mapping. All lunasin fractions partially purified by anion exchange and immunoaffinity column chromatography suppress colony formation induced by the ras-oncogene and inhibit core H3-histone acetylation. During seed development, lunasin peptide appears 5 weeks after flowering and persists in the mature seed. Western blot analysis of different soybean varieties and commercially available soy proteins shows the presence of the peptide in varying amounts. These results demonstrate the feasibility of producing large quantities of natural lunasin from soybean for animal and human studies.

Soybean protein fraction digested with neutral protease preparation, “Peptidase R”, produced by Rhizopus oryzae, stimulates innate cellular immune system in mouse

“…Kim et al [5] reported that the peptide corresponding to residues 83 to 89 of soybean glycinin showed cytotoxic activity toward P388D1, a mouse monocyte macrophage cell line. In addition, Jeong et al [6] found that lunasin (a small subunit of 2S albumin) inhibited the carcinogenesis of mouse fibroblast NIH 3T3 cells induced by chemical carcinogens such as DMBA and MNU. These reports suggest that soybean proteins and their digests might be utilized as functional food additives with hypocholesterolemic and antitumor activities.…”

Lunasin: A promising polypeptide for the prevention and treatment of cancer

“…This extraction method usually results in a crude protein containing lunasin, which requires further purification. Ion-exchange column chromatography has been used for the purification of lunasin extracted from soybean and barley in previous studies, and the principal material used in the ion-exchange column is bio-gel resin AG1-X4 with a particle size of between 100 and 200 mesh, and the volume of the ion-exchange column is 5.0x50 cm with a filled height of 40 cm (27,28). In addition, gel electrophoresis, western blotting and mass spectrometry are also used for the qualitative analysis and quantitative determination of lunasin (29,30).…”

1997-2012: Fifteen Years of Research on Peptide Lunasin

“…First studies performed with mammalian cells revealed that lunasin did not affect their morphology and proliferation. However, this peptide acted preventing their transformation induced by chemical carcinogens-7,12-dimethylbenz[a]anthracene (DMBA) and 3-methylcholanthrene (MCA) [33,34], viral and ras-oncogenes [33,35,36]. These experiments made lunasin be considered a "watchdog" agent in the cell nucleus that once the transformation event occurs, it acts as a surrogate tumor suppressor that tightly binds to deacetylated core histones disrupting the balance between acetylation-deacetylation, which is perceived by the cell as abnormal and leads to cell death [37].…”

“…When the cells are in the steady-state conditions, the core H3 and H4 histones are mostly deacetylated, as a repressed state. When cells were treated with peptide lunasin and well-known deacetylase inhibitor sodium butyrate, histone acetylation was inhibited in C3H10T1/2 fibroblasts and breast cancer MCF-7 cells [33,36]. Furthermore, lunasin has been demonstrated to compete with different histone acetyltransferase enzymes (HATs), such as yGCN5 and PCAF, inhibiting the acetylation and repressing the cell cycle progression [24,25,28].…”