próteins

Próteins are large, complex molecules that play a central role in nearly all biological processes. They are polymers built from amino acids linked by peptide bonds. The sequence of amino acids (the primary structure) determines the protein’s properties and function.

Proteins fold into intricate three-dimensional shapes through non-covalent interactions and sometimes disulfide bonds, giving rise to secondary, tertiary, and quaternary structures. Proper folding is essential for activity; misfolding can lead to loss of function or aggregation. Denaturation from heat, pH changes, or chemicals can disrupt structure.

Functions of próteins are diverse: enzymes catalyze biochemical reactions; structural proteins provide support (collagen, keratin); transport proteins move substances (hemoglobin, membrane transporters); signaling and regulatory proteins control cellular processes; antibodies defend against pathogens; hormones regulate physiology; motor proteins drive movement.

Synthesis occurs in cells via gene expression. Transcription produces messenger RNA, which is translated by ribosomes. Transfer RNA brings amino acids to the growing peptide chain. Post-translational modifications (phosphorylation, glycosylation) diversify function. Proteins are degraded by proteasomes and enzymes when damaged.

Dietary próteins supply essential amino acids that the body cannot synthesize. Complete proteins provide all essential amino acids (e.g., animal proteins); plant proteins may be complementary. Severe protein deficiency can cause malnutrition; imbalances or misfolding are linked to diseases, including neurodegenerative disorders.