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![[Figure 7]](mh5163fig7mag.jpg)
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Figure 7
The proposed mechanism of zNt-FDH based on superimposition of formate and THF in the active site between the structures of the zNt-FDH–formate and the zNt-FDH–THF complexes. (a) A comparison of the structures of the formate complex (green C atoms) and THF complex (yellow C atoms) forms. Both formate and THF molecules are shown in ball-and-stick representation; the residues His106, Ser108 and Asp142 of the formate complex (salmon) and the THF complex (cyan) are shown in stick representation. (b) The S atom of β-mercaptoethanol (BME) attacks the substrate (10-FTHF) to form an intermediate state and release the product (THF). Asp142 activates the water molecule or directly attacks the C atom of the formyl group. BME and the formyl group bind to Asp142; thus, breakage of the sulfur–carbon bond underlies the biochemical process. The water molecule attacks the formyl group to form the formate during the hydrolase reaction. After hydrolysis, the products (formate and THF) can be stabilized by the catalytic residues (His106 and Asp142) in the active site. |
![[Figure 7]](mh5163fig7.jpg)
 | STRUCTURAL BIOLOGY |
ISSN: 2059-7983
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