Purification and characterization of methylmalonyl-CoA epimerase from Propionibacterium shermanii

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Abstract
Methylmalonyl-CoA epimerase (EC 5.1.99.1), which specifically interconverts the (2R)- and (2S)-epimers of methylmalonyl-CoA, was purified 95-fold from P. shermanii by a new method that affords apparently homogeneous enzyme, in 80-100 mg quantities, in yields representing about 40% of the activity in cell-free extracts. The specific activity of the purified enzyme, 10.1 .mu.kat/mg, is much greater than previously reported. Native methylmalonyl-CoA epimerase has MW about 33,000, and apparently consists of 2 identical subunits. The purified enzyme is stable indefinitely when stored at -20.degree. C and pH 8.5, but contrary to previous reports it is not unusually acid-stable. The activity of methylmalonyl-CoA epimerase is increased by Co2+, and to a smaller extent by Ni2+, Nm2+ and Zn2+.