McCarthy A A, Baker H M, Shewry S C, Kagawa T F, Saafi E, Patchett M L, Baker E N
School of Biological Sciences, University of Auckland, Auckland, New Zealand.
Acta Crystallogr D Biol Crystallogr. 2001 May;57(Pt 5):706-8. doi: 10.1107/s0907444901002050. Epub 2001 Apr 24.
Methylmalonyl-CoA epimerase (MMCE) is an enzyme that interconverts the R and S epimers of methylmalonyl-CoA in the pathway that links propionyl-CoA with succinyl-CoA. This is used for both biosynthetic and degradative processes, including the breakdown of odd-numbered fatty acids and some amino acids. The enzyme has been expressed in Escherichia coli both as the native enzyme and as its selenomethionine (SeMet) derivative. Crystals of both forms have been obtained by vapour diffusion using monomethylether PEG 2000 as precipitant. The native MMCE crystals are orthorhombic, with unit-cell parameters a = 56.0, b = 114.0, c = 156.0 A, and the SeMet-MMCE crystals are monoclinic, with unit-cell parameters a = 43.6, b = 78.6, c = 89.4 A, beta = 92.0 degrees; both diffract to better than 2.8 A resolution.
甲基丙二酰辅酶A差向异构酶（MMCE）是一种在丙酰辅酶A与琥珀酰辅酶A连接途径中使甲基丙二酰辅酶A的R型和S型差向异构体相互转化的酶。这一过程用于生物合成和降解过程，包括奇数脂肪酸和一些氨基酸的分解。该酶已在大肠杆菌中表达，既有天然酶形式，也有其硒代甲硫氨酸（SeMet）衍生物形式。两种形式的晶体均通过气相扩散法，以单甲醚聚乙二醇2000作为沉淀剂获得。天然MMCE晶体为正交晶系，晶胞参数a = 56.0、b = 114.0、c = 156.0 Å，而SeMet-MMCE晶体为单斜晶系，晶胞参数a = 43.6、b = 78.6、c = 89.4 Å，β = 92.0°；两者的衍射分辨率均优于2.8 Å。
