Biochemistry of Amino Acids - A. Meister 1961

General Biochemistry and Physiology of Amino Acid Metabolism
Amino Acid Racemization
alpha,epsilon-Diaminopimelic Acid Racemase

Shortly after the discovery of meso-a,ε-diaminopimelic acid [379–381] and LL-a,ε-diaminopimelic acid [382] in several bacterial Cells, a bacterial decarboxylase was found in some of them, converting the meso-form of diaminopimelic acid into L-Lysine and carbon dioxide [240]. Initially, it was noted that LL-a,ε-diaminopimelic acid was susceptible to decarboxylation. However, it later turned out that the apparent decarboxylation of the LL-isomer was due to The conversion of this isomer into the meso-form, which is the true substrate of the specific decarboxylase. The enzyme responsible for the interconversion of the meso- and LL-forms of a,ε-diaminopimelic acid was isolated from the cells of a mutant strain of Escherichia coli requiring lysine for growth. This enzyme is of particular interest because it catalyzes the racemization of a single asymmetric center in an amino acid molecule that possesses two asymmetric centers:

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The DD-isomer is not racemized by this enzyme. The Study of this enzyme system is not yet complete; in particular, it has not yet been established whether Pyridoxal phosphate participates in this reaction. The enzyme is inactivated by dialysis, while thiol compounds restore The activity of the dialyzed preparations.



Last update: 06/08/2026

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