Toxalbumins are toxic plant protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

s that disable ribosome

Ribosome

A ribosome is a component of cells that assembles the twenty specific amino acid molecules to form the particular protein molecule determined by the nucleotide sequence of an RNA molecule....

s and thereby inhibit protein synthesis, producing severe cytotoxic effects in multiple organ systems. They are dimers

Protein dimer

In biochemistry, a dimer is a macromolecular complex formed by two, usually non-covalently bound, macromolecules like proteins or nucleic acids...

 held together by a disulfide bond

Disulfide bond

In chemistry, a disulfide bond is a covalent bond, usually derived by the coupling of two thiol groups. The linkage is also called an SS-bond or disulfide bridge. The overall connectivity is therefore R-S-S-R. The terminology is widely used in biochemistry...

 and comprise a lectin

Lectin

Lectins are sugar-binding proteins that are highly specific for their sugar moieties. They play a role in biological recognition phenomena involving cells and proteins. For example, some viruses use lectins to attach themselves to the cells of the host organism during infection...

 (carbohydrate-binding protein) part which binds to the cell membrane and enables the toxin part to gain access to the cell contents. Toxalbumins are similar in structure to the toxins found in cholera

Cholera

Cholera is an infection of the small intestine that is caused by the bacterium Vibrio cholerae. The main symptoms are profuse watery diarrhea and vomiting. Transmission occurs primarily by drinking or eating water or food that has been contaminated by the diarrhea of an infected person or the feces...

, tetanus

Tetanus

Tetanus is a medical condition characterized by a prolonged contraction of skeletal muscle fibers. The primary symptoms are caused by tetanospasmin, a neurotoxin produced by the Gram-positive, rod-shaped, obligate anaerobic bacterium Clostridium tetani...

, diphtheria

Diphtheria

Diphtheria is an upper respiratory tract illness caused by Corynebacterium diphtheriae, a facultative anaerobic, Gram-positive bacterium. It is characterized by sore throat, low fever, and an adherent membrane on the tonsils, pharynx, and/or nasal cavity...

 and botulinum; and their physiological and toxic properties are similar to those of viperine

Viperinae

The Viperinae, or viperines, are a subfamily of venomous vipers found in Europe, Asia and Africa. They are distinguished by their lack of the heat-sensing pit organs that characterize their sister group, the Crotalinae. Currently, 12 genera and 66 species are recognized...

 snake venom

Snake venom

Snake venom is highly modified saliva that is produced by special glands of certain species of snakes. The glands which secrete the zootoxin are a modification of the parotid salivary gland of other vertebrates, and are usually situated on each side of the head below and behind the eye,...

.

Toxalbumins notably are present in the plant families Leguminosae and Euphorbiaceae

Euphorbiaceae

Euphorbiaceae, the Spurge family are a large family of flowering plants with 300 genera and around 7,500 species. Most are herbs, but some, especially in the tropics, are also shrubs or trees. Some are succulent and resemble cacti....

, occurring for instance in Robinia pseudoacacia, Abrus precatorius, Jatropha curcas

Jatropha curcas

Jatropha curcas is a species of flowering plant in the spurge family, Euphorbiaceae, that is native to the American tropics, most likely Mexico and Central America. It is cultivated in tropical and subtropical regions around the world, becoming naturalized in some areas...

, Croton gratissimus

Croton gratissimus

Croton gratissimus is a tropical African shrub or small tree with corky bark, growing to 8 m and belonging to the family of Euphorbiaceae or spurge...

and Ricinus communis. Typical toxalbumins are abrin

Abrin

Abrin is a toxalbumin that is found in the seeds of a plant called lucky bean, rosary pea or jequirity pea. Abrin is similar to but far more deadly than ricin, a toxin found in the seeds of the castor oil plant.-Physical Properties:...

 and ricin

Ricin

Ricin , from the castor oil plant Ricinus communis, is a highly toxic, naturally occurring protein. A dose as small as a few grains of salt can kill an adult. The LD50 of ricin is around 22 micrograms per kilogram Ricin , from the castor oil plant Ricinus communis, is a highly toxic, naturally...

. Ingestion of seed containg toxalbumins is not necessarily fatal as the hard seed coat will withstand digestion, unless the seed has been pierced, as would happen in the making of necklaces, prayer beads or bracelets, and even then the toxalbumin is likely to be digested and thereby rendered harmless. Toxalbumins injected intravenously or subcutaneously or inhaled in powdered form, though, are highly toxic. A latent period of hours to days may follow with no sensible signs of distress, after which symptoms of nausea, vomiting and diarrhoea will appear, followed by delirium, seizures, coma, and death. Seen from an evolutionary viewpoint, toxalbumins developed as a deterrent to consumption of seeds.

Toxalbumins were first described in about 1890 by Ludwig Brieger (1849-1919) and Sigmund Fraenkel

Sigmund Fraenkel

Sigmund Fraenkel or Sigmund Fränkel was a Polish-born chemist who lived and worked in Austria, and is notable for being the head of the Ludwig-Spiegler-Stiftung in Vienna from 1904 and his work in the field of Physiological chemistry, notably on the chemistry of the thyroid gland...

 (1868-1939), associates of the organic chemist Eugen Baumann

Eugen Baumann

Eugen Baumann was a German chemist. He was one of the first people to create polyvinyl chloride , and, together with Carl Schotten, he discovered the Schotten-Baumann reaction.-Life:...

. Brieger first used the term toxin

Toxin

A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...

.