Succinate dehydrogenase stereospecificity

Aconitate dehydratase, succinate dehydrogenase, and fumarase yield stereospecific products. Labeling experiments with in methyl and carboxyl carbons of acetyl-CoA or in all of the carbons of oxaloacetate yield the following results in terms of the intermediates or product formed. 

In addition to their efficiency, enzymes are also remaikable for their specificity. Each enzyme usually catalyses one specific reaction, and sometimes, only one specific reactant, called substrate, is converted into products. For example, succinate dehydrogenase is an enzyme that exclusively catalyses the oxidation of succinic acid, and not any other carboxylic acid. One of the other important aspects of enzyme catalysis is their stereospecificity. For example, proteases only hydrolyse the derivatives of L-amino acids and not the corresponding D-amino acids. This can be extremely valuable in understanding enzyme mechanisms. At the other extreme, are the enzymes that catalyse families of reactions, such as the esterases, which are enzymes that catalyse the hydrolysis of esters independent of the molecular groups attached to the ester linkage. 

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