Multiple choice The geometric or structural changes within the substrate molecule is brought by lyases ligases hydrolases isomerases Reveal answer Fill a bubble to check yourself D Correct answer Explanation These enzymes catalyse geometric or structural changes within one molecule. According to the type of isomerism, they may be called racemases, epimerases, cis-trans-isomerases, isomerases, tautomerases, mutases or cycloisomerases.