The enzyme decarboxylase catalyses the following step
The enzyme decarboxylase catalyses the following step
conversion of citric acid to $\mathrm{cis}$ aconitic acid
fumaric acid to malic acid
oxalosuccinic acid to $\alpha$-ketoglutaric acid
malic acid to oxaloacetic acid.
Solution
Oxalosuccinate is decarboxylated to form $\alpha$-ketoglutarate through the enzyme decarboxylase. It is one of the step involved in Krebs' cycle. It releases one molecule of $\mathrm{CO}_2$.
$\begin{aligned} & \text { Oxalosuccinate } \stackrel{\text { Decarboxylase }}{\mathrm{Mg}^{2+}} \\ & \alpha \text {-ketoglutarate }+\mathrm{CO}_2 \\ & \end{aligned}$