Krebs cycle step 7

From Proteopedia

Step 7 of the Krebs cycle: Fumarase

Figure: Formation of L-Malate

L-malate is formed out of fumarate by adding water to the double bond; therefore, the reaction type is a hydration. The reaction process is unusual becaue the first step is the addition of OH^-. As a result, a negativley charged carbanion is formed. The addition of the proton on the opposite side of the hydroxy group, leads to the formation of L-malate. The catalysing enzyme fumarase is highly stereospecific, which can be seen from the fact that only L-malate is formed as a product and not a mixture of D-malate and L-malate.