Isomerases are a broad class of enzymes which catalyze structural change in a single molecule in biological systems. These structural changes can be extremely various, from very simple modifications such as the reorientation from levo to dextro alignment in the following amino acid:
COO- alanine COO-
| racemase |
H3N+--C--H ------> H--C--N+H3
Up to the fantastically complex topology
topological modifications in DNA Topoisomerases
, which uncoil and recoil long strands of DNA
to allow reading and copying.