Methyl‐CoenzymeMReductase

Coordination of Coenzyme M and Its Derivatives on NiII(tetraazacycle) Complexes: A Model for the Active Site of Methyl Coenzyme M Reductase

“…sis suggests the coordination of an oxygen atom, [2,3] while both nitrogen and oxygen atoms appear to be bound to nickel according to the EXAFS data. [5] Although nickel complexes of N 4 macrocycles have been reported as models of the MCR active site, [6,7] attempts to synthesize those containing methyl coenzyme M (MeSCoM) and coenzyme M (HSCoM) remain very limited.…”

“…[1] Recently, the structures of inactive states of MCR have been determined by crystallographic analysis, and those of MCR silent and MCR ox1-silent from Methanobacterium thermoautrophicum are shown in Figure 1 (a and b). [2] The active site contains a nickel tetrahydrocorphinoid cofactor F 430 as a prosthetic group (Figure 2), [2][3][4] and the nickel is additionally coordinated at an axial position by a sulfonate oxygen of the heterodisulfide CoBS-SCoM for the MCR silent or a thiolato (or thiol) sulfur of the coenzyme M for the MCR ox1-silent . At the other axial position, Gln147 is weakly interacting with the nickel atom, while the coordination mode of the glutamine residue has not been established.…”

Spectroscopic and Kinetic Studies of the Reaction of Bromopropanesulfonate with Methyl-coenzyme M Reductase

“…High resolution crystal structures for three EPR-silent and inactive Ni(II) states of this enzyme have been determined: MCR silent , MCR ox1-silent , and MCR red1-silent (7,12,13). These states have several common features: the central nickel atom of F 430 is coordinated by four planar tetrapyrrole nitrogen atoms and a lower axial oxygen ligand contributed by the carbonyl oxygen of the side chain of Gln-␣Ј147.…”

“…In the Ni(II) silent form of MCR, the upper axial nickel ligand is the sulfonate oxygen of CoBS-SCoM, whereas, in the Ni(II) ox1-silent form, this site is occupied by the thiol(ate) group of CoM-S(H) ( Fig. 1) (7,12,13). A five-coordinate form of Ni(II)-MCR red1-silent , lacking an upper axial ligand, has also been observed in the crystal structure (13).…”

Methyl‐Coenzyme M Reductase and its Nickel Corphin Coenzyme F 430 in Methanogenic Archaea

“…Until now crystal structures of MCR are only available for inactive, EPR-silent forms, in which the nickel of F 430 is in the Ni(II) oxidation state [108][109][110] (for a review see [111]). The structure of the inactive enzyme, the best structure resolved to 1.16 Å, is characterized by a series of α helices arranged in a compact form with an ellipsoidal shape of about 120 A ϫ 85 A ϫ 80 A or 120 ϫ 85 ϫ 80 A exponent 3 (A ϭ Angstrom).…”