Styrene oxide isomerase
Styrene oxide isomerase (SOI) is an enzyme (EC 5.3.99.7) that catalyses isomerization of styrene oxide to phenylacetaldehyde. SOI is one of the rate-limiting step enzyme in bacterial styrene degradation pathways.
Structural highlightsSOI is an integral membrane protein with four transmembrane helices. It forms a novel homo-trimeric assembly with a structural fold reminiscent of ion channels. The trimeric organization, crucial for its function, is mediated by a ferric heme b prosthetic group positioned between two protomers. This ferric heme b acts as a Lewis acid, interacting with the epoxide oxygen atom of epoxide substrate, facilitating the ring-opening. ApplicationsSOI catalyzes the Meinwald rearrangement, a Lewis-acid-catalyzed isomerization of aryl epoxides into aryl acetaldehydes. Aryl epoxides are valuable chemical precursors used in numerous industrial applications. Traditionally, converting aryl epoxides to carbonyl compounds requires harsh, corrosive chemicals and high temperatures, which result in product mixtures and environmental pollution. In contrast, SOI is highly stereospecific, making it a promising alternative for catalyzing this important reaction in industrial applications.
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ReferencesReferences
1. Panke S, Witholt B, Schmid A, Wubbolts MG. 1998. Towards a Biocatalyst for (S)-Styrene Oxide Production: Characterization of the Styrene Degradation Pathway of Pseudomonas sp. Strain VLB120. Appl Environ Microbiol 64:. https://doi.org/10.1128/AEM.64.6.2032-2043.1998 2. Nobuya Itch, Kunimasa Hayashi, Keisaku Okada, Takeshi Ito, Naoyuki Mizuguchi, Characterization of Styrene Oxide Isomerase, a Key Enzyme of Styrene and Styrene Oxide Metabolism in Corynehacterium sp., Bioscience, Biotechnology, and Biochemistry, Volume 61, Issue 12, 1 January 1997, Pages 2058–2062, https://doi.org/10.1271/bbb.61.2058 3. Khanppnavar, B., Choo, J.P.S., Hagedoorn, PL. et al. Structural basis of the Meinwald rearrangement catalysed by styrene oxide isomerase. Nat. Chem. (2024). https://doi.org/10.1038/s41557-024-01523-y