Figure 20-18a


Figure 20-18b

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X-Ray structure of P. shermanii methylmalonyl-CoA mutase in complex with 2-carboxypropyl-CoA and AdoCbl.
(a) The catalytically active α subunit in which the N-terminal domain is cyan with the β strands of its α/β barrel orange, and the C-terminal domain is pink. The 2-carboxypropyl-CoA (magenta) and AdoCbl (green) are drawn in space-filling form. The 2-carboxypropyl-CoA passes through the center of the α/β barrel and is oriented such that the methylmalonyl group of methylmalonyl-CoA would contact the corrin ring of the AdoCbl, which is sandwiched between the enzyme's N- and C-terminal domains.
(b) The arrangement of the AdoCbl and 2-carboxypropyl-CoA molecules which, together with the side chain of His 610, are represented in stick form colored according to atom type (AdoCbl and His C green, 2-carboxypropyl-CoA C cyan, N blue, O red, P magenta, and S yellow). The corrin ring's Co atom is represented by a lavender sphere and the α/β barrel's β strands are represented by orange ribbons. The view is similar to that in Part a. Note that the DMB group (bottom) has swung away from the corrin ring (seen edgewise) to be replaced by the side chain of His 610 from the C-terminal domain and that the 5'-deoxyadenosyl group is unseen (due to disorder). [Based on an X-ray structure by Philip Evans, MRC Laboratory of Molecular Biology, Cambridge, U.K. PDBid 7REQ.]