Isomerases facilitate intramolecular rearrangements in which bonds why are some enzymes classified as hydrolases broken and formed. They convert one isomer to another, meaning that the end product has the same molecular formula but a different physical structure. Stereoisomers have the same ordering of individual bonds and the same connectivity but the three-dimensional arrangement of bonded atoms differ. The sub-categories of isomerases containing racemases, epimerases and cis-trans isomers are examples of enzymes catalyzing the interconversion of stereoisomers. Intramolecular lyases, oxidoreductases and transferases catalyze the interconversion of structural isomers.
Isomers close in energy can interconvert easily and are often seen in comparable proportions. Instead, tracer perturbation can overcome these technical difficulties if there are two forms of the unbound enzyme. As equilibrium is established again, the radiolabeled substrate and product are tracked to determine energetic information. Enzyme-catalyzed reactions each have a uniquely assigned classification number.
A molecule with multiple chiral carbons has two forms at each chiral carbon. This category is not broken down any further. Some of these catalyzed reactions involve the breaking of a ring structure. A ketose is then formed and the ring is closed again. C2 to form enzymes that aid in protein digestion double bond between C1 and C2. C1 oxygen is protonated by the catalytic residue, accompanied by the deprotonation of the endiol C2 oxygen. To close the fructose ring, the reverse of ring opening occurs and the ketose is protonated.
After the substrate binds to the enzyme, the first Asp deprotonates the third carbon from one side of the molecule. The second Asp is located on the opposite side of the active side and it protonates the molecule, effectively adding a proton from the back side. These coupled steps invert stereochemistry at the third carbon. A proposed mechanism for chorismate mutase. Transition-state analogue inhibitors of chlorismate mutase. It is thought that this binding stabilizes the transition state through electrostatic effects, accounting for the dramatic increase in the reaction rate in the presence of the mutase or upon addition of a specifically-placed cation in the active site. The adjacent carbon, C2, is what are the enzymes produced in the pancreas from the opposite face to yield a double bond.