As by the name the reaction they catalyse is to change the chemical compound in its isomeric form or we can use isomerase enzymes in transfer of groups within the molecules to yield isomeric frorms.
e.g
the enzyme phosphohexose isomerase catalyzes the reversible isomerization of glucose6-phosphate, an aldose to fructose 6-phosphate, a ketone

There are very many enzymes involved. A few from glycolysis are: hexokinase and glucokinase, phosphohexose isomerase, phosphofructokinase, pyruvate kinase; from pyruvate decarboxylation are pyruvate dehydrogenase phosphatase and pyruvate dehydrogenase kinase; and a few from the Kreb's cycle are: aconitase, alpha-ketoglutamate dehydrogenase, succinate thiokinase, and fumarase.

Isomerase breaks down glucose into fructose

to isomer foods, isomerase can produce cat food and dog biscuits

Isomerase is consider as a major class of enzymes that catalyze the isomerization process. It can be found in where a bonds are broken and formed.