polyamiineja

Polyamiineja, or polyamines, are organic compounds containing two or more amino groups. At physiological pH they carry multiple positive charges, enabling strong interactions with nucleic acids, proteins, and membranes. The most abundant natural polyamines are putrescine, spermidine, and spermine, found in virtually all living cells. They are essential for growth, development, and cellular homeostasis.

Biosynthesis and turnover: In animals and many other organisms, polyamiineja are synthesized from the amino acid ornithine via ornithine decarboxylase to form putrescine, which is then converted to spermidine and spermine by specific synthases. A parallel pathway exists in some microbes. Polyamiineja are degraded by amine oxidases and acetyltransferases and can be recycled through cellular transport mechanisms. Intracellular levels are tightly regulated to balance proliferation and stability of biomolecules.

Biological roles: Polyamiineja stabilize DNA and RNA structures, influence chromatin organization, and regulate transcription and translation. They modulate the function of enzymes and ion channels and play roles in RNA processing, protein synthesis, and cell-cycle progression. Their availability is closely linked to growth, development, and responses to cellular stress.

Medical and practical relevance: Deregulated polyamiineja metabolism is associated with cancer and other diseases, making their pathways targets for research and therapy. Inhibitors of ornithine decarboxylase have been explored as anticancer agents. In laboratory and clinical contexts, polyamiineja serve as indicators of cellular status, and dietary intake contributes to systemic levels through foods such as meat, dairy, and some vegetables.

See also: polyamine metabolism, ornithine decarboxylase, polyamine transport.