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Phytohaemagglutinin (PHA, or phytohemagglutinin) is a lectin found in plants, especially certain legumes. PHA actually consists of two closely related proteins, called leucoagglutinin (PHA-L) and PHA-E. The letters E and L indicate these proteins agglutinate erythrocytes and leukocytes. Phytohaemagglutinin has carbohydrate-binding specificity for a complex oligosaccharide containing galactose, N-acetylglucosamine, and mannose.^[2]

It is found in the highest concentrations in uncooked red kidney beans and white kidney beans (also known as cannellini),^[3] and it is also found in lower quantities in many other types of green beans and other common beans (Phaseolus vulgaris), as well as broad beans (Vicia faba) such as fava beans.^[4] It has a number of physiological effects and is used in medical research. In high doses, it is a toxin.

The lectin has a number of effects on cell metabolism; it induces mitosis, and affects the cell membrane in regard to transport and permeability to proteins. It agglutinates most mammalian red blood cell types.

As a toxin, it can cause poisoning in monogastric animals, such as humans, through the consumption of raw or improperly prepared kidney beans. Measured in haemagglutinating units (hau), a raw red kidney bean may contain up to 70,000 hau. This can be reduced to safe levels by correct cooking (boiling for at least 30 minutes at 100 °C/ 212 °F).^[5] Insufficient cooking, such as in a slow cooker at 80 °C/ 176 °F, however, can increase this danger and raise the available hau up to fivefold.^[6] Beans also contain alpha amylase inhibitor, but not in sufficient quantities to affect the digestion of starch after consumption of beans.^[7]

Poisoning can be induced from as few as five raw beans, and symptoms occur within three hours, beginning with nausea, then vomiting, which can be severe and sustained (profuse), followed by diarrhea. Recovery occurs within four or five hours of onset, usually without the need for any medical intervention.

In medicine these proteins are useful and are used as a mitogen to trigger T-lymphocyte cell division and to activate latent HIV-1 from human peripheral lymphocytes. In neuroscience, anterograde tracing is a research method that uses the protein product phytohaemagglutinin PHA-L as a molecular tracer that can be taken up by the cell and transported across the synapse into the next cell thereby tracing the path of axonal projections and relative connections that nerve impulses travel beginning with the source located at the perikaryon (cell body or soma) and through the presynaptic part located on neuron's efferent axon all the way to the point of termination at the efferent synapse which then provides input to another neuron.^[8]

Lymphocytes cultured with phytohaemagglutinin can be used for karyotype analysis.

History

PHA was discovered by Dr. Peter Nowell, codiscoverer of the Philadelphia chromosome in the 1960s.

References

^ Hamelryck, T. W.; Dao-Thi, M. H.; Poortmans, F.; Chrispeels, M. J.; Wyns, L.; Loris, R. (1996). "The crystallographic structure of phytohemagglutinin-L". The Journal of Biological Chemistry. 271 (34): 20479–20485. doi:10.1074/jbc.271.34.20479. PMID 8702788.
^ "PHA-E specification sheet Medicago AB: Phytohaemagglutinin" (PDF). Retrieved 2010-03-14.
^ "Kidney Beans". The world's healthiest foods. Retrieved 2007-11-05.
^ "Bad Bug Book (2012)" (PDF). Foodborne Pathogenic Microorganisms and Natural Toxins Handbook: Phytohaemagglutinin. United States Food and Drug Administration. p. 254. Retrieved 2013-12-27.
^ "Bad Bug Book (2012)" (pdf). Foodborne Pathogenic Microorganisms and Natural Toxins Handbook: Phytohaemagglutinin. Food and Drug Administration. 2012. Retrieved 26 December 2013. Consumers should boil the beans for at least 30 minutes to ensure that the product reaches sufficient temperature
^ Bad Bug Book (2009). "Foodborne Pathogenic Microorganisms and Natural Toxins Handbook Phytohaemagglutinin". US Food and Drug Administration. Retrieved 26 December 2013.
^ Layer P, Carlson GL, DiMagno EP (1985). "Partially purified white bean amylase inhibitor reduces starch digestion in vitro and inactivates intraduodenal amylase in humans". Gastroenterology. 88 (6): 1895–902. PMID 2581844.
^ Carlson, Neil R. (2007). Physiology of Behavior, 9th ed. Boston: Pearson Education, Inc. p. 144. ISBN 0-205-46724-5.

External links

Phytohemagglutinins at the US National Library of Medicine Medical Subject Headings (MeSH)

UpToDate Contents

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English Journal

A comparative study of physicochemical characteristics and functionalities of pinto bean protein isolate (PBPI) against the soybean protein isolate (SPI) after the extraction optimisation.

Tan ES1, Ying-Yuan N2, Gan CY3.
Food chemistry.Food Chem.2014 Jun 1;152:447-55. doi: 10.1016/j.foodchem.2013.12.008. Epub 2013 Dec 10.
Optimisation of protein extraction yield from pinto bean was investigated using response surface methodology. The maximum protein yield of 54.8 mg/g was obtained with the optimal conditions of: temperature=25 °C, time=1 h and buffer-to-sample ratio=20 ml/g. PBPI was found to obtain high amount of e
PMID 24444960

Determinants and short-term physiological consequences of PHA immune response in lesser kestrel nestlings.

Rodríguez A1, Broggi J, Alcaide M, Negro JJ, Figuerola J.
Journal of experimental zoology. Part A, Ecological genetics and physiology.J Exp Zool A Ecol Genet Physiol.2014 May 8. doi: 10.1002/jez.1868. [Epub ahead of print]
Individual immune responses are likely affected by genetic, physiological, and environmental determinants. We studied the determinants and short-term consequences of Phytohaemagglutinin (PHA) induced immune response, a commonly used immune challenge eliciting both innate and acquired immunity, on le
PMID 24807828

Select human milk oligosaccharides directly modulate peripheral blood mononuclear cells isolated from 10-d-old pigs.

Comstock SS1, Wang M1, Hester SN2, Li M1, Donovan SM1.
The British journal of nutrition.Br J Nutr.2014 Mar 14;111(5):819-28. doi: 10.1017/S0007114513003267. Epub 2013 Oct 17.
Infant formulas lack the complex mixture of oligosaccharides found in human milk. These human milk oligosaccharides (HMO) may be pivotal to the development of the neonatal immune system. Few comprehensive analyses of the effects of HMO on immune cells from neonates have been undertaken. Herein, the
PMID 24131853

Japanese Journal

UV plumage color is an honest signal of quality in male budgerigars

GRIGGIO Matteo,ZANOLLO Valeria,HOI Herbert
Ecological research 25(1), 77-82, 2010-01-01
NAID 10027355470

DHMEQ, a novel nuclear factor-κB inhibitor, induces selective depletion of alloreactive or phytohaemagglutinin-stimulated peripheral blood mononuclear cells, decreases production of T helper type 1 cytokines, and blocks maturation of dendritic cells

Nishioka Chie,Ikezoe Takayuki,Yang Jing,Umezawa Kazuo,Yokoyama Akihito
Immunology 124, 198-205, 2008-06-00
NAID 120002187914

Related Pictures

★リンクテーブル★

リンク元	「フィトヘマグルチニン」「PHA」「植物性血球凝集素」

「フィトヘマグルチニン」

Available protein structures:
Pfam	structures
PDB	RCSB PDB; PDBe; PDBj
PDBsum	structure summary

Legume lectin domain
	Crystal structure of PHA-L (PDB 1fat)
Identifiers
Symbol	Lectin_legB
Pfam	PF00139
Pfam clan	CL0004
InterPro	IPR001220
PROSITE	PDOC00278
SCOP	1lem
SUPERFAMILY	1lem
Available protein structures:
Pfam	structures
PDB	RCSB PDB; PDBe; PDBj
PDBsum	structure summary