Lektiinit

Lektiinit, known in English as lectins, are a diverse group of non-enzymatic proteins that bind specifically to carbohydrates on glycoproteins and glycolipids. This carbohydrate-recognition enables a variety of biological interactions, including cell agglutination in some lectins and recognition of cell-surface glycans.

Distribution and roles: Lectins occur across life, but are especially abundant in plants, notably seeds and tubers. In plants they serve defense against pests and pathogens and may influence seed germination and pollen interactions. In animals and microbes, lectins participate in cell–cell interactions and host-pathogen recognition.

Classification and examples: Lectins are classified by binding properties and structure, including C-type lectins (calcium-dependent) and galectins (Ca2+-independent). Specificity varies: some bind mannose or glucose (as concanavalin A does), others bind N-acetylglucosamine (WGA) or fucose (UEA-I). Common laboratory lectins include concanavalin A (ConA), wheat germ agglutinin (WGA), and Ulex europaeus agglutinin I (UEA-I).

Laboratory use: Lectins are tools in glycoprotein research and histology. They enable affinity purification of glycoproteins, mapping of glycans, and labeling of cells or tissues by lectin histochemistry or flow cytometry.

Nutrition and safety: Some lectins are toxic when raw; processing such as cooking or soaking reduces activity. For example, proper cooking reduces legumes' lectin content. Overall, processed plant foods are safe for most people; dietary claims advocating strict lectin-free diets are not supported by strong evidence.