Soybean agglutinins (SBA) also known as soy bean lectins (SBL) are lectins found in soybeans. It is a family of similar

legume lectin {{Infobox protein family , Symbol = Lectin_legB , Name = Legume lectin domain (or L-type lectin domain) , image = PDB 1lem EBI.jpg , width = , caption = Structure of the monosaccharide binding site of lentil lectin.{{cite journal , vauthors=L ...

s. As a lectin, it is an

antinutrient Antinutrients are natural or synthetic compounds that interfere with the absorption of nutrients. Nutrition studies focus on antinutrients commonly found in food sources and beverages. Antinutrients may take the form of drugs, chemicals that natur ...

that chelates minerals. In human foodstuffs, less than half of this lectin is deactivated even with extensive cooking (boiling for 20 minutes).

Characteristics

SBAs have a molecular weight of 120 kDa and an

isoelectric point The isoelectric point (pI, pH(I), IEP), is the pH at which a molecule carries no net electrical charge or is electrically neutral in the statistical mean. The standard nomenclature to represent the isoelectric point is pH(I). However, pI is also u ...

near pH 6.0 SBA preferentially binds to

oligosaccharide An oligosaccharide (/ˌɑlɪgoʊˈsækəˌɹaɪd/; from the Greek ὀλίγος ''olígos'', "a few", and σάκχαρ ''sácchar'', "sugar") is a saccharide polymer containing a small number (typically two to ten) of monosaccharides (simple sug ...

structures with terminal

α-helix The alpha helix (α-helix) is a common motif in the secondary structure of proteins and is a right hand-helix conformation in which every backbone N−H group hydrogen bonds to the backbone C=O group of the amino acid located four residues ...

β-sheet The beta sheet, (β-sheet) (also β-pleated sheet) is a common motif of the regular protein secondary structure. Beta sheets consist of beta strands (β-strands) connected laterally by at least two or three backbone hydrogen bonds, forming a g ...

linked N-acetylgalactosamine, and to a lesser extent,

galactose Galactose (, '' galacto-'' + ''-ose'', "milk sugar"), sometimes abbreviated Gal, is a monosaccharide sugar that is about as sweet as glucose, and about 65% as sweet as sucrose. It is an aldohexose and a C-4 epimer of glucose. A galactose molecu ...

residues. Binding can be blocked by substitutions on penultimate sugars, such as

fucose Fucose is a hexose deoxy sugar with the chemical formula C6H12O5. It is found on ''N''-linked glycans on the mammalian, insect and plant cell surface. Fucose is the fundamental sub-unit of the seaweed polysaccharide fucoidan. The α(1→3) li ...

attached to the penultimate galactose in

blood group A blood type (also known as a blood group) is a classification of blood, based on the presence and absence of antibodies and inherited antigenic substances on the surface of red blood cells (RBCs). These antigens may be proteins, carbohydrates ...

B. Soybean lectin has a metal binding site, which is conserved among beans. SBA binds to intestinal epithelial cells, causing inflammation and intestinal permeability, and is a major factor in acute inflammation from raw soybean meal fed to animals. Studies on rats fed SBA had complex changes: With increasing doses of soybean agglutinin, the activities of

aspartate aminotransferase Aspartate transaminase (AST) or aspartate aminotransferase, also known as AspAT/ASAT/AAT or (serum) glutamic oxaloacetic transaminase (GOT, SGOT), is a pyridoxal phosphate (PLP)-dependent transaminase enzyme () that was first described by Arthur ...

linearly increased in plasma and decreased plasma insulin content without decrease in blood glucose levels. Consumption of soybean agglutinin resulted in a depletion of lipid and an overgrowth of small intestine and pancreas in rats. Meanwhile, poor growth of spleen and kidneys and pancreatic hypertrophy was observed in the soybean agglutinin-fed rats.

Applications

An important application for SBA is the separation of

pluripotent stem cells Pluripotency: These are the cells that can generate into any of the three Germ layers which imply Endodermal, Mesodermal, and Ectodermal cells except tissues like the placenta. According to Latin terms, Pluripotentia means the ability for many thin ...

from human bone marrow. Cells fractionated by SBA do not produce graft vs host disease and can be used in

bone marrow transplantation Hematopoietic stem-cell transplantation (HSCT) is the transplantation of multipotent hematopoietic stem cells, usually derived from bone marrow, peripheral blood, or umbilical cord blood in order to replicate inside of a patient and to produce ...

across

histocompatibility Histocompatibility, or tissue compatibility, is the property of having the same, or sufficiently similar, alleles of a set of genes called human leukocyte antigens (HLA), or major histocompatibility complex (MHC). Each individual expresses many uni ...

barriers. SBA binding has been investigated as a useful tool for detection of stomach cancer.

References

{{Soy Lectins Stem cells Soy products