isomerasas

Isomerasas, known in English as isomerases, are a broad class of enzymes that catalyze the rearrangement of atoms within a molecule, converting one isomer into another without changing the molecule’s overall chemical formula. They enable changes in connectivity or stereochemistry, including the conversion between constitutional isomers, epimers, diastereomers, or cis-trans configurations, and they can promote intramolecular rearrangements such as group migrations or peptide-bond isomerization.

Isomerases are classified as EC class 5 in the Enzyme Commission system. They include several subtypes: racemases and epimerases, which invert configuration at a stereocenter; cis-trans isomerases, which switch between cis and trans arrangements; and mutases, which relocate functional groups within a molecule. This diversity reflects the wide range of cellular processes that require rapid interconversion of isomeric forms.

Prominent examples include triosephosphate isomerase, which interconverts dihydroxyacetone phosphate and glyceraldehyde-3-phosphate in glycolysis; glucose-6-phosphate isomerase, which interconverts glucose-6-phosphate and fructose-6-phosphate in carbohydrate metabolism; ribose-5-phosphate isomerase, which rearranges sugar phosphates in nucleotide biosynthesis; phosphoglucomutase, a mutase that shifts phosphate groups in glucose phosphates; and alanine racemase, which converts L-alanine to D-alanine in bacterial cell-wall synthesis. Peptidyl-prolyl cis-trans isomerases regulate protein folding by catalyzing cis-trans isomerization at proline residues.

Isomerases are found across all domains of life and often function in the cytosol, mitochondria, plastids, or other compartments. They may require cofactors such as metal ions or pyridoxal phosphate and can be essential for metabolism, development, and signaling.