Styrene monooxygenase
A styrene monooxygenase (SMO; EC 1.14.14.11) is an enzyme that catalyzes the chemical reaction
- styrene + FADH2 + O2 ↔ (S)-2-phenyloxirane + FAD + H2O
| Styrene monooxygenase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| EC number | 1.14.14.11 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| |||||||||
as the first step of the aerobic styrene degradation pathway.[1] The product 2-phenyloxirane is also known as styrene oxide and can be converted by a styrene oxide isomerase (SOI) to obtain phenylacetaldehyde, which can be transformed into the key-intermediate phenylacetic acid by a phenylacetaldehyde dehydrogenase (PAD).
The enzyme belongs to the group of oxidoreductases according to the EC classification and is dependent on FAD as cofactor, thus it was classified as an external flavoprotein monooxygenase (designated as type E).[2][3] It forms a two-component system with a reductase (StyB, StyA2B). The reductase utilizes solely NADH to reduce the FAD, which is then transferred to the styrene monooxygenase (StyA, StyA1). Two types of that enzyme are described so far: StyA/StyB (designated E1), first described from Pseudomonas species, and StyA1/StyA2B (designated E2), first described from Actinobacteria. The E1-type is more abundant in nature and comprises a single monooxygenase (StyA) supported by a single reductase (StyB), whereas the E2-type has a major monooxygenase (StyA1) which is supported by fusion protein of a monooxygenase and reductase (StyA2B). The latter one is the source of reduced FAD for the monooxygenase subunits and has some side activity as a monooxygenase. So far all styrene monooxygenases perform enantioselective epoxidations of styrene and chemically analogous compounds, which makes them interesting for biotechnological applications.[2]
References
- Mooney A, Ward PG, O'Connor KE (August 2006). "Microbial degradation of styrene: biochemistry, molecular genetics, and perspectives for biotechnological applications". Applied Microbiology and Biotechnology. 72 (1): 1–10. doi:10.1007/s00253-006-0443-1. PMID 16823552.
- Montersino S, Tischler D, Gassner GT, van Berkel WJ (September 2011). "Catalytic and structural features of flavoprotein hydroxylases and epoxidases". Advanced Synthesis & Catalysis. 353 (13): 2301–19. doi:10.1002/adsc.201100384.
- van Berkel WJ, Kamerbeek NM, Fraaije MW (August 2006). "Flavoprotein monooxygenases, a diverse class of oxidative biocatalysts" (PDF). Journal of Biotechnology. 124 (4): 670–89. doi:10.1016/j.jbiotec.2006.03.044. PMID 16712999.