Epimerase and racemase

Epimerases and racemases are isomerase enzymes that catalyze the inversion of stereochemistry in biological molecules.^[1] Racemases catalyze the stereochemical inversion around the asymmetric carbon atom in a substrate having only one center of asymmetry. Epimerases catalyze the stereochemical inversion of the configuration about an asymmetric carbon atom in a substrate having more than one center of asymmetry, thus interconverting epimers.

Human epimerases include methylmalonyl-CoA epimerase, involved in the metabolic breakdown of the amino acids alanine, isoleucine, methionine and valine,^[2] and UDP-glucose 4-epimerase, which is used in the final step of galactose metabolism - catalyzing the reversible conversion of UDP-galactose to UDP-glucose.

References

↑ Tanner, ME. (2002). "Understanding nature's strategies for enzyme-catalyzed racemization and epimerization". Acc. Chem. Res. 35 (4): 237–246. doi:10.1021/ar000056y. PMID 11955052.
↑ http://www.britannica.com/science/isomerase

External links

http://medical-dictionary.thefreedictionary.com/racemase
http://medical-dictionary.thefreedictionary.com/epimerase
Entry Term Epimerases at the US National Library of Medicine Medical Subject Headings (MeSH)

Isomerases: Epimerase and racemases (EC 5.1)

5.1.1: Amino acids	Amino-acid racemase: Phenylalanine racemase (ATP-hydrolysing) Serine racemase

5.1.2: Hydroxy acids	Mandelate racemase

5.1.3: Carbohydrates	UDP-glucose 4-epimerase

5.1.99: Other	Methylmalonyl CoA epimerase

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