Peptidketten

Peptidketten are polymers made of amino acids connected by peptide bonds. They can be short, as in dipeptides or tripeptides, or long enough to qualify as polypeptides, which may fold into functional proteins. The sequence and composition of amino acids determine the properties and roles of the chain.

Peptide bonds form through a condensation reaction between the carboxyl group of one amino acid and the amino group of the next. This creates a repeating backbone with a direction from the amino terminus (N-terminus) to the carboxyl terminus (C-terminus). The peptide bond itself is planar and has partial double-bond character, giving the backbone limited rotation and defining the chain’s conformation. Rotation mainly occurs around the bonds adjacent to the alpha carbon, allowing various three-dimensional shapes.

The primary structure of a peptidketten is its linear amino acid sequence. Longer chains can adopt secondary structures such as alpha helices and beta sheets, which in turn contribute to tertiary structure (the overall three-dimensional fold) and, for multi-chain assemblies, quaternary structure.

Biologically, peptidketten are synthesized in cells by ribosomes translating mRNA, producing polypeptides that may then be processed or modified. Chemically, they can be assembled by solid-phase or other peptide synthesis methods. Degradation occurs via proteolysis, where proteases hydrolyze peptide bonds to release constituent amino acids.

Peptidketten fulfill diverse roles, including hormones, neurotransmitters, antimicrobial agents, and structural components. Their function is closely tied to sequence, length, and three-dimensional structure, making them central to biochemistry and molecular biology.