Phytohaemagglutinin

phytohemagglutinin L

Phytohaemagglutinin

Phytohaemagglutinin (PHA) is a lectin found in plants, particularly in the legume family. It is most commonly extracted from the common bean (Phaseolus vulgaris). PHA is known for its ability to agglutinate red blood cells and stimulate mitosis in lymphocytes.

Structure and Function

Phytohaemagglutinin is a glycoprotein composed of two closely related proteins, PHA-L and PHA-E, which differ in their affinity for different types of glycoconjugates. PHA-L has a higher affinity for complex carbohydrates, while PHA-E binds more readily to simple sugars. These proteins are capable of binding to specific carbohydrate moieties on the surface of cells, leading to cell agglutination and mitogenic activity.

Biological Activity

PHA is widely used in immunology and cell biology due to its ability to induce cell division in T lymphocytes. This property makes it a valuable tool for studying cell cycle regulation, immune response, and cancer research. PHA can also be used to stimulate lymphocyte proliferation in in vitro assays, which is useful for immunological studies and diagnostic purposes.

Toxicity

While PHA has important applications in research, it is also known to be toxic if ingested in large quantities. Raw or undercooked kidney beans contain high levels of PHA, which can cause severe gastrointestinal distress, including nausea, vomiting, and diarrhea. Proper cooking methods, such as boiling beans for at least 10 minutes, can significantly reduce the PHA content and render the beans safe for consumption.

Applications

Medical Research

In medical research, PHA is used to study lymphocyte activation and proliferation. It is also employed in cytotoxicity assays to evaluate the effects of various compounds on immune cells. Additionally, PHA is used in chromosome studies to induce mitosis in lymphocyte cultures, facilitating the examination of chromosomal abnormalities.

Agriculture

In agriculture, PHA is studied for its potential role in plant defense mechanisms. It is believed to contribute to the plant's ability to resist pathogen attacks by binding to pathogen surface proteins and inhibiting their activity.

Related Pages

• Lectin
• Common bean
• Lymphocyte
• Mitosis
• Immune response
• Cell cycle
• Cancer research
• Cytotoxicity
• Chromosome
• Pathogen