polipeptidkötést

Polipeptidkötést, also known as a peptide bond, is a type of covalent chemical bond formed between amino acids during protein synthesis. Specifically, it is an amide bond that links the carboxyl group of one amino acid to the amino group of another. This process, called dehydration synthesis or condensation, releases a molecule of water. The formation of a peptide bond is catalyzed by ribosomes, the cellular machinery responsible for translating messenger RNA into protein sequences.

Each peptide bond has a partial double bond character due to resonance, which makes the bond rigid and planar. This rigidity influences the overall three-dimensional structure of proteins. The sequence of amino acids linked by peptide bonds forms a polypeptide chain, which is the primary structure of a protein. The directionality of the polypeptide chain is defined by the N-terminus (the free amino group) and the C-terminus (the free carboxyl group). A series of amino acids joined by peptide bonds is called a polypeptide, and when this chain folds into a functional three-dimensional structure, it is referred to as a protein. The strength of the peptide bond is significant, requiring considerable energy to break, typically through hydrolysis, which is the reverse reaction of dehydration synthesis. This bond is fundamental to all life, as it forms the backbone of proteins essential for countless biological functions.