A coordination chemist's view of the active sites of mononuclear molybdenum enzymes

作者：Basu P^*; Stolz JF; Smith MT

来源：Current Science, 2003, 84(11): 1412-1418.

A comparison of the coordination environment of twelve structurally characterized mononuclear molybdenum-containing enzymes revealed many similarities that helped, define specific features of the active sites. Using bond distances and angles, the types of bonds and terminal groups of significance were identified. For example, a distance between molybdenum and oxygen atoms ranging from 1.6 to 1.8 Angstrom was considered as a Mo=O bond. The dithiolene sulphur to molybdenum single bond distances fluctuated around 2.40 Angstrom. In most cases, the sulphur-sulphur interaction within the co-factors is weak, with distances above 3.00 Angstrom, but both trimethylamine N-oxide and dissimilatory nitrate reductase (i.e. NapA) show strong sulphur-sulphur interactions with distances closer to 2.80 Angstrom. In addition, the dithiolene bite angle (S-Mo-S) was observed to be directly affected by the distance of the sulphurs from the metal centre. The bite angle is very small for co-factors that are further away from the molybdenum atom, as observed in TMAOR. A small bite angle is suggestive of ligand dissociation.

• 出版日期2003-6-10