Molybdenum cofactor structure

Figure 1 Iron-molybdenum cofactor structures in resting (left) and hypothetical dinitrogen-bound states (right)...

J. L. Johnson, B. E. Mainline, K. V. Rajagopalan and B. H. Arison, The Pterin Component of the Molybdenum Cofactor Structural characterization of two fluorescent derivatives,/ Biol Chem., 1984,259, 5414-5422. 

Molybdenum, tris(phenylenedithio)-structure, 1,63 Molybdenum alkoxides physical properties, 2,346 synthesis, 2,339 Molybdenum blue liquid-liquid extraction, 1,548 Molybdenum cofactor, 6,657 Molybdenum complexes acrylonitrile, 2,263 alkoxides, 3,1307 alkoxy carbonyl reactions, 2,355 alkyl, 3,1307 alkyl alkoxy reactions, 2,358 alkyl peroxides oxidation catalyses, 6,342 allyl, 3,1306... 

Fig. 4. Structure of the iron molybdenum cofactor, FeMoco (after Chan, Kim, and Rees, (4) Bolin et al. (5) and Mayer et al. (7)). The FeMoco is ligated, within the a subunits of the a2j82 tetrameric structure, by residues Hisa442 and Cysa275 (Avl residue numbers).

Kisker, C., Schindelin, H. and Rees, D.C. (1997). Molybdenum cofactor - containing enzymes structure and mechanisms. Annu. Rev. of Biochem., 66, 233-267... 

Kisker, C., Sghindelin, H., Baas, D., Retey, j., Megkenstogk, R. U., and Kroneck, P. M. a structural comparison of molybdenum cofactor-containing enzymes, FEMS Microbiol Rev 1998, 22, 503-521. 

Figure 15. Possible structures for the iron—molybdenum cofactor of nitrogenase.

Fig. 15. Structure of the homocitrate component of the nitrogenase iron-molybdenum cofactor.

Figure 17 Proposed structure for the molybdenum cofactor of the oxomolybdoenzymes172...

The molybdenum cofactor is often assumed to be involved in dimerisa-tion of NR, either as a bridge as in an early structural model (Pan Nason, 1978), or more indirectly. This hypothesis is no longer valid, since it has been shown that in bakers yeast, an organism which lacks the MoCo biosynthetic pathway, a transgenic, MoCo-less tobacco NR is nevertheless dimeric (Truong et al., 1991). This is in agreement with the observa-... 

Figure 2 The structures ofthe MPT cofactor subfamilies. The boxes represent subfamilies of molybdenum and tungsten enzymes with high sequence homology. Cofactor structure type determined aby x-ray crystallography from the listed source bby EXAFS.

The conversion of dinitrogen to ammonia is one of the important processes of chemistry. Whereas the technical ammonia synthesis requires high temperature and pressure (1), this reaction proceeds at room temperature and ambient pressure in nature, mediated by the enzyme nitrogenase (2). There is evidence that N2 is bound and reduced at the iron-molybdenum cofactor (FeMoco), a unique Fe/Mo/S cluster present in the MoFe protein of nitrogenase. Although detailed structural information on nitrogenase has been available for some time (3), the mechanism of N2 reduction by this enzyme is still unclear at the molecular level. Nevertheless, it is possible to bind and reduce dinitrogen at simple mono- and binuclear transition-metal systems which allow to obtain mechanistic information on elemental steps involved... 

Molybdenum cofactor, its biological importance and structural and synthetic aspects 93H(35)1551. 

The Taylor route is also very useful in the synthesis of more complex structures as demonstrated in the total synthesis of deoxyurothione (381), ( )-urothion (382) <89JA285>, and analogous 6,7-dihydrothieno[3,2- ]pterins (384) which are model substances of the oxidative breakdown product (383), termed form B of the molybdenum cofactor (399) <88JOC5839>. 

Synthetic and structural aspects about the extremely labile molybdenum cofactor (Moco) have been summarized <93H(35)l55l> and indicate fundamental difficulties in building up the molybdenum enedithiole complex. 

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