Tyrosyl group
-Tyrosyl_group_V.1.svg)
-Tyrosyl_group_V.1.svg)
The tyrosyl group , according to IUPAC 2-amino-3- (4-hydroxyphenyl) propanoyl- , abbreviated Tyr- , is the amino acid residue of tyrosine . It occurs in peptide bonds such as kyotorphine ( dipeptide ). As a functional group, it represents a special monovalent (univalent) α- aminoacyl group, since it is formed from an α-amino acid (English amino ac id) by eliminating the hydroxyl group of the carboxy group . The tyrosyl group contains a stereocenter, so there are two enantiomeric forms, the L form and the D form. If no stereochemical descriptors are given, the natural L- tyrosyl group [synonym: ( S ) -yrosyl group] is almost always meant, which is derived from the proteinogenic amino acid L- tyrosine.
Tyrosyl tRNA synthetase
The human tyrosyl tRNA synthetase, which was previously only known as the essential enzyme in protein synthesis, exhibits cytokine-like activities after proteolytic cleavage into two fragments. These peptide fragments are novel elements of the modulation of the local tissue reaction in the direction of a cellular suicide program and can be viewed as a highly specific adaptation of peptide modules to more than one biological function that is dependent on the environmental conditions.