cysteiny

Cysteiny is a term that appears in some contexts to refer to compounds or moieties derived from the amino acid cysteine, or to the cysteinyl fragment in peptides. It is not a standard, standalone chemical name with a single, universal definition. In peptide and protein chemistry, the prefix cysteinyl- or adjective cysteinyl describes a cysteine residue or a cysteine-derived linkage within a molecule. For example, cysteinylglycine is a dipeptide consisting of cysteine linked to glycine, and the cysteinyl moiety is present in the tripeptide glutathione (gamma-glutamylcysteinylglycine), a key intracellular antioxidant.

Cysteine itself is a sulfur-containing amino acid with a thiol side chain (–CH2–SH). The thiol group allows cysteine to form disulfide bonds, which stabilize protein structure and participate in redox signaling. Cysteine residues can undergo various post-translational modifications, including S-nitrosylation, S-palmitoylation, and S-glutathionylation. In nutrition, cysteine is semi-essential and can be synthesized from methionine via the transsulfuration pathway; it is also obtained from dietary proteins. Clinically, derivatives such as N-acetylcysteine are used for mucolytic therapy and as antioxidants in different conditions.

In summary, cysteiny is not a widely standardized term; its meaning is context-dependent and typically relates to the cysteinyl moiety or cysteine-derived components in larger molecules. See cysteine, cysteinyl, cystine, and related compounds for broader context.