moleculeprotein

A moleculeprotein is a biologically functional macromolecule composed of one or more polypeptide chains that fold into defined three-dimensional structures. Each polypeptide is a linear sequence of amino acids linked by peptide bonds; the sequence is encoded by genes and determines the protein's shape and function. Many moleculeproteins require cofactors or prosthetic groups to perform their functions.

Proteins exhibit four levels of structure: primary, secondary, tertiary, and quaternary. The primary structure is the amino acid sequence; secondary includes alpha helices and beta sheets; tertiary is the overall three-dimensional fold; and quaternary describes assemblies of multiple chains. Folding is guided by intra- and intermolecular interactions, and chaperone proteins assist in preventing misfolding.

Functions are diverse: enzymes catalyze reactions; structural proteins provide support; transport proteins move substances across membranes; signaling and receptor proteins mediate communication; immune proteins recognize threats; motor proteins generate movement.

Synthesis and regulation: in cells, ribosomes translate mRNA into polypeptides, which then fold and undergo post-translational modifications such as phosphorylation, glycosylation, and proteolysis. Protein levels are controlled by synthesis and degradation, allowing rapid responses to cellular conditions.

Studying moleculeproteins employs techniques such as mass spectrometry, X-ray crystallography, cryo-electron microscopy, and nuclear magnetic resonance. Knowledge of protein structure and function underpins drug design, biotechnology, and understanding diseases linked to folding and misregulation, including neurodegenerative and metabolic disorders.