CysteinAminosäureresten

CysteinAminosäureresten refers to the form of the amino acid cysteine after it has been incorporated into a protein. Cysteine is unique among the common amino acids due to its thiol side chain (-SH). This thiol group is highly reactive and plays crucial roles in protein structure and function. The most well-known function of cysteine residues in proteins is the formation of disulfide bonds (S-S). These covalent bonds form between the sulfur atoms of two cysteine residues, either within the same polypeptide chain or between different chains. Disulfide bonds are vital for stabilizing the three-dimensional structure of many proteins, particularly extracellular proteins, and are important for their proper folding and function.

Beyond disulfide bond formation, cysteine residues can also participate in other important interactions. The thiol group can act as a nucleophile, participating in catalytic mechanisms of enzymes. It can also bind to metal ions, forming metalloproteins. Furthermore, cysteine residues are targets for post-translational modifications, such as S-nitrosylation, S-glutathionylation, and phosphorylation, which can alter protein activity, localization, or stability. The precise environment and neighboring residues surrounding a cysteineAminosäureresten within a protein can significantly influence its reactivity and the roles it plays. Therefore, understanding the state and context of cysteine residues is fundamental to comprehending protein biochemistry and function.