polyamine metabolic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways involving polyamines, any organic compound containing two or more amino groups. [ISBN:0198506732]

Polyamine metabolism is a fundamental biological process essential for cell growth, proliferation, and differentiation. It involves the biosynthesis, catabolism, and regulation of polyamines, which are small, positively charged molecules with multiple amino groups. The primary polyamines in mammals are putrescine, spermidine, and spermine.

The biosynthesis of polyamines begins with the decarboxylation of ornithine to putrescine by ornithine decarboxylase (ODC). Putrescine is then converted to spermidine by spermidine synthase, which adds aminopropyl groups from decarboxylated S-adenosyl methionine (dcSAM). Finally, spermine is synthesized from spermidine by spermine synthase, using another molecule of dcSAM.

Polyamine catabolism is primarily mediated by the enzyme spermidine/spermine N1-acetyltransferase (SSAT), which acetylates the terminal amino group of spermidine and spermine. Acetylated polyamines are then further degraded by polyamine oxidase (PAO), generating hydrogen peroxide and other products.

Regulation of polyamine metabolism is complex and involves multiple mechanisms. ODC is the rate-limiting enzyme in polyamine biosynthesis and is highly regulated by various factors, including growth factors, hormones, and cellular stress. SSAT activity is also regulated, with increased activity typically associated with cellular stress and aging.

Polyamines play a crucial role in numerous cellular functions. They interact with DNA, RNA, and proteins, affecting their structure and function. Polyamines promote cell growth by stimulating protein synthesis and DNA replication. They also participate in cell signaling pathways and modulate the activity of various enzymes.

Dysregulation of polyamine metabolism is associated with various diseases, including cancer, neurodegenerative disorders, and cardiovascular disease. In cancer, polyamine levels are often elevated, contributing to increased cell proliferation and tumor growth. Conversely, deficiencies in polyamines can lead to developmental defects and impaired immune function.

Polyamine metabolism is a highly conserved process across species, highlighting its fundamental importance in maintaining cellular homeostasis and promoting normal biological functions.'
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Proteins (8)

Compounds (8)