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Lunasin is a peptide found in soy and some cereal grains that, since 1996, has been the subject of research focusing on cancer, cholesterol and cardiovascular disease and inflammation. [1]
Lunasin is a peptide that can be found in soy, barley, wheat, [2] and rye. It is also found in grains originating in the American continents, such as Amaranthus hypochondriacus . [3] This polypeptide was originally isolated, purified, and sequenced from soybean seed in 1987. Although uncertain about the peptide’s biological activity, the Japanese team of researchers described it as a 43-amino acid peptide, noting specifically the unusual poly (L-aspartic acid) sequence at the carboxyl terminus. [4] [5] Subsequent research by Alfredo Galvez in the laboratory of Ben de Lumen at the University of California–Berkeley identified the peptide as a subunit of the cotyledon-specific 2S albumin. [6] The name of the protein was chosen from the Filipino word lunas, which means "cure". [7] [8] Lunasin was patented as a biologic molecule in 1999 by de Lumen and Galvez. [9]
The biological activity of lunasin was discovered by Galvez while working in the laboratory of de Lumen at UC Berkeley. [10]
There has been much research interest in the biomedical aspects of lunasin but the high cost of synthesizing lunasin made experimentation difficult. [11] This limitation has been overcome by the development of methods to isolate highly purified lunasin from soybean white flake, a byproduct of soybean processing. [12] In laboratory and animal experiments lunasin has shown anti-carcinogenic activity that suggests it may have chemopreventive potential. [13]
In 2014, a local news program reported that a person with ALS named Mike McDuff had experienced dramatic improvements in speech, swallowing and limb strength while taking a supplement regimen containing lunasin. [14] ALSUntangled [15] investigated and was able to confirm that Mike McDuff had progressive muscular atrophy, a "lower motor neuron" form of ALS, and really did experience dramatic and objective improvements. [16] Since one possible explanation for these improvements was the use of lunasin, Dr. Richard Bedlack of the Duke ALS Clinic decided to perform a clinical trial. Fifty people with ALS were put on the exact Lunasin containing regimen that Mike McDuff had taken and were followed for a year. The trial finished in September 2017. Unfortunately, there was no evidence that lunasin slowed, stopped or reversed ALS in any of the trial participants. Gastrointestinal side effects were more common than expected in trial participants, including cases of constipation severe enough to warrant hospitalization. [17] Bedlack concluded that lunasin was not a useful treatment for ALS and that Mike McDuff likely had some other explanation for his ALS reversal such as an ALS mimic syndrome or a genetic resistance to the disease. [18]
A protease is an enzyme that catalyzes proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products. They do this by cleaving the peptide bonds within proteins by hydrolysis, a reaction where water breaks bonds. Proteases are involved in numerous biological pathways, including digestion of ingested proteins, protein catabolism, and cell signaling.
The soybean, soy bean, or soya bean is a species of legume native to East Asia, widely grown for its edible bean, which has numerous uses.
Aspartic acid, is an α-amino acid that is used in the biosynthesis of proteins. The L-isomer of aspartic acid is one of the 22 proteinogenic amino acids, i.e., the building blocks of proteins. D-aspartic acid is one of two D-amino acids commonly found in mammals. Apart from a few rare exceptions, D-aspartic acid is not used for protein synthesis but is incorporated into some peptides and plays a role as a neurotransmitter/neuromodulator.
Phytic acid is a six-fold dihydrogenphosphate ester of inositol, also called inositol hexaphosphate, inositol hexakisphosphate (IP6) or inositol polyphosphate. At physiological pH, the phosphates are partially ionized, resulting in the phytate anion.
Cysteine proteases, also known as thiol proteases, are hydrolase enzymes that degrade proteins. These proteases share a common catalytic mechanism that involves a nucleophilic cysteine thiol in a catalytic triad or dyad.
Aspergillopepsin I is an enzyme. This enzyme catalyses the following chemical reaction
Soy protein is a protein that is isolated from soybean. It is made from soybean meal that has been dehulled and defatted. Dehulled and defatted soybeans are processed into three kinds of high protein commercial products: soy flour, concentrates, and isolates. Soy protein isolate has been used since 1959 in foods for its functional properties.
Aspartic proteases are a catalytic type of protease enzymes that use an activated water molecule bound to one or more aspartate residues for catalysis of their peptide substrates. In general, they have two highly conserved aspartates in the active site and are optimally active at acidic pH. Nearly all known aspartyl proteases are inhibited by pepstatin.
N-Acetylaspartylglutamic acid is a peptide neurotransmitter and the third-most-prevalent neurotransmitter in the mammalian nervous system. NAAG consists of N-acetylaspartic acid (NAA) and glutamic acid coupled via a peptide bond.
Pepstatin is a potent inhibitor of aspartyl proteases. It is a hexa-peptide containing the unusual amino acid statine, having the sequence Isovaleryl-Val-Val-Sta-Ala-Sta (Iva-Val-Val-Sta-Ala-Sta). It was originally isolated from cultures of various species of Actinomyces due to its ability to inhibit pepsin at picomolar concentrations. It was later found to inhibit nearly all acid proteases with high potency and, as such, has become a valuable research tool, as well as a common constituent of protease inhibitor cocktails.
AFPep is an orally-active, cyclic, 9-amino acid, peptide with a molecular weight of 969 daltons and is derived from the anti-oncogenic active site of alpha fetoprotein (AFP). Using the standard amino acid abbreviations, AFPep has the sequence cyclo(EKTOVNOGN), where O is hydroxyproline. This peptide has been shown in experimental animal models to be efficacious in the prevention and treatment of ER+ breast cancer.
Cathepsin D is a protein that in humans is encoded by the CTSD gene. This gene encodes a lysosomal aspartyl protease composed of a protein dimer of disulfide-linked heavy and light chains, both produced from a single protein precursor. Cathepsin D is an aspartic endo-protease that is ubiquitously distributed in lysosomes. The main function of cathepsin D is to degrade proteins and activate precursors of bioactive proteins in pre-lysosomal compartments. This proteinase, which is a member of the peptidase A1 family, has a specificity similar to but narrower than that of pepsin A. Transcription of the CTSD gene is initiated from several sites, including one that is a start site for an estrogen-regulated transcript. Mutations in this gene are involved in the pathogenesis of several diseases, including breast cancer and possibly Alzheimer disease. Homozygous deletion of the CTSD gene leads to early lethality in the postnatal phase. Deficiency of CTSD gene has been reported an underlying cause of neuronal ceroid lipofuscinosis (NCL).
Renin inhibitors are pharmaceutical drugs inhibiting the activity of renin that is responsible for hydrolyzing angiotensinogen to angiotensin I, which in turn reduces the formation of angiotensin II that facilitates blood pressure.
Plant defensins are a family of primitive, highly stable, cysteine-rich defensins found in plants that function to defend them against pathogens and parasites. Defensins are integral components of the innate immune system and belong to the ancient superfamily of antimicrobial peptides (AMPs). AMPs are also known as host defense peptides (HDPs), and they are thought to have diverged about 1.4 billion years ago before the evolution of prokaryotes and eukaryotes. They are ubiquitous in almost all plant species, functionally diverse, and their primary structure varies significantly from one species to the next, except for a few cysteine residues, which stabilize the protein structure through disulfide bond formation. Plant defensins usually have a net positive charge due to the abundance of cationic amino acids and are generally divided into two classes. Those in the class II category contain a C-terminal pro-peptide domain of approximately 33 amino acids and are targeted to the vacuole, while the class I defensins lack this domain and mature in the cell wall. Unlike their class I counterparts, class II plant defensins are relatively smaller, and their acidic C-terminal prodomain is hypothesized to contribute to their vacuolar targeting. The first plant defensins were discovered in barley and wheat in 1990 and were initially designated as γ-thionins. In 1995, the name was changed to 'plant defensin' when it was identified that they are evolutionarily unrelated to other thionins and were more similar to defensins from insects and mammals.
Kunitz soybean trypsin inhibitor is a type of protein contained in legume seeds which functions as a protease inhibitor. Kunitz-type Soybean Trypsin Inhibitors are usually specific for either trypsin or chymotrypsin. They are thought to protect seeds against consumption by animal predators.
Arginylglycylaspartic acid (RGD) is the most common peptide motif responsible for cell adhesion to the extracellular matrix (ECM), found in species ranging from Drosophila to humans. Cell adhesion proteins called integrins recognize and bind to this sequence, which is found within many matrix proteins, including fibronectin, fibrinogen, vitronectin, osteopontin, and several other adhesive extracellular matrix proteins. The discovery of RGD and elucidation of how RGD binds to integrins has led to the development of a number of drugs and diagnostics, while the peptide itself is used ubiquitously in bioengineering. Depending on the application and the integrin targeted, RGD can be chemically modified or replaced by a similar peptide which promotes cell adhesion.
Kunitz domains are the active domains of proteins that inhibit the function of protein degrading enzymes or, more specifically, domains of Kunitz-type are protease inhibitors. They are relatively small with a length of about 50 to 60 amino acids and a molecular weight of 6 kDa. Examples of Kunitz-type protease inhibitors are aprotinin, Alzheimer's amyloid precursor protein (APP), and tissue factor pathway inhibitor (TFPI). Kunitz STI protease inhibitor, the trypsin inhibitor initially studied by Moses Kunitz, was extracted from soybeans.
In molecular biology, the Bowman–Birk protease inhibitor family of proteins consists of eukaryotic proteinase inhibitors, belonging to MEROPS inhibitor family I12, clan IF. They mainly inhibit serine peptidases of the S1 family, but also inhibit S3 peptidases.
Sunflower trypsin inhibitor (SFTI) is a small, circular peptide produced in sunflower seeds, and is a potent inhibitor of trypsin. It is the smallest known member of the Bowman-Birk family of serine protease inhibitors.
Elvira de Mejia is a biochemist and food scientist, currently working as a professor of Food Sciences and Human Nutrition at the University of Illinois at Urbana–Champaign. She is an expert in the areas of food science, food toxicology, and chemoprevention.
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