fehérjéken

Fehérjéken, or proteins in English, are large, complex organic molecules made up of amino acid chains that fold into specific three‑dimensional structures. They are essential macromolecules in all living organisms and perform a broad range of biological functions covering enzymatic activity, structural support, transport, signaling, and immune defense.

The basic chemical building block of all proteins is L‑α‑amino acids. The twenty standard amino acids differ in their side chains, which determines the protein’s properties and its capacity to interact with other molecules. Proteins are synthesized in cells by ribosomes that read the coding sequence of messenger RNA. Translation fidelity and regulated folding mechanisms ensure that each newly formed polypeptide acquires the functional shape required for its particular role.

Proteins are classified on the basis of structure into primary, secondary (α‑helix and β‑sheet), tertiary, and quaternary levels. Enzymes, a major subclass of proteins, are catalysts that accelerate biochemical reactions by lowering activation energy. Other important protein groups include antibodies, which recognize specific antigens; structural proteins such as collagen and keratin; transport proteins like hemoglobin and albumin; and signaling proteins such as insulin and growth factors.

In nutritional science, proteins are vital sources of essential amino acids that mammals cannot synthesize. Dietary protein intake is normally expressed in grams per kilogram of body weight, and an average adult requires about 0.8 g/kg/day for maintenance; higher amounts are recommended for growth, recovery from injury, or intense physical activity. Common dietary protein sources are meat, fish, dairy, legumes, grains, nuts, and seeds.

The study of proteins, protein chemistry, and structural biology, particularly through techniques such as X‑ray crystallography, nuclear magnetic resonance spectroscopy, and cryo‑electron microscopy, has expanded the understanding of cellular life processes and aided drug design, biotechnology, and medical diagnostics.