page_title: Lanosterol 14 alpha-demethylase
section_title: Structure
hierarchical_section_title: Lanosterol 14 alpha-demethylase / Structure
caption_attribution_description: English: Structure of lanosterol 14 α-demethylase (CYP51)
context_page_description: Lanosterol 14α-demethylase is a cytochrome P450 enzyme that is involved in the conversion of lanosterol to 4,4-dimethylcholesta-8,14,24-trien-3β-ol. The cytochrome P450 isoenzymes are a conserved group of proteins that serve as key players in the metabolism of organic substances and the biosynthesis of important steroids, lipids, and vitamins in eukaryotes. As a member of this family, lanosterol 14α-demethylase is responsible for an essential step in the biosynthesis of sterols. In particular, this protein catalyzes the removal of the C-14α-methyl group from lanosterol. This demethylation step is regarded as the initial checkpoint in the transformation of lanosterol to other sterols that are widely used within the cell.
context_section_description: Although the structure of 14α-demethylase may vary substantially from one organism to the next, sequence alignment analysis reveals that there are six regions in the protein that are highly conserved in eukaryotes. These include residues in the B' helix, B'/C loop, C helix, I helix, K/β1-4 loop, and β-strand 1-4 that are responsible for forming the surface of the substrate binding cavity. Homology modeling reveals that substrates migrate from the surface of the protein to the enzyme's buried active site through a channel that is formed in part by the A' alpha helix and the β4 loop. Finally, the active site contains a heme prosthetic group in which the iron is tethered to a thiolate ligand on a conserved cysteine residue. This group also binds diatomic oxygen at the sixth coordination site, which is eventually incorporated onto the substrate.
caption: Structure of lanosterol 14α-demethylase (CYP51), as identified by Podust et al.
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