Accepted name: endo-cleaving rubber dioxygenase
Reaction: Cleavage of cis-1,4-polyisoprene polymers into a mixture of compounds, including a C20 compound ((4Z,8Z,12Z,16Z,20Z,24Z)-4,8,12,16,20,24-hexamethyl-28-oxononacosa-4,8,12,16,20,24-hexaenal), a C25 compound ((4Z,8Z,12Z,16Z,20Z)-4,8,12,16,20-pentamethyl-24-oxopentacosa-4,8,12,16,20-pentaenal), a C30 compound ((4Z,8Z,12Z,16Z)-4,8,12,16-tetramethyl-20-oxohenicosa-4,8,12,16-tetraenal), and larger isoprenologes such as C35, C40, C45, and higher analogues.
Other name(s): latex clearing protein; lcp (gene name); roxB (gene name)
Systematic name: cis-1,4-polyisoprene:oxygen dioxygenase (endo-cleaving)
Comments: The enzyme catalyses the cleavage of the double bonds in natural and synthetic rubber, producing a mixture of C20, C25, C30, and higher oligo-isoprenoids with ketone and aldehyde groups at their ends. Two unrelated bacterial enzymes are known to possess this activity - the enzyme from Streptomyces sp. K30 (Lcp) contains a b-type cytochrome, while the enzyme from Xanthomonas sp. 35Y, (RoxB) contains two c-type cytochromes. Both enzymes attack the substrate at random locations, and are not able to cleave the C35 or smaller products into shorter fragments.
1.  Tsuchii, A. and Takeda, K. Rubber-degrading enzyme from a bacterial culture. Appl. Environ. Microbiol. 56 (1990) 269–274. [PMID: 16348100]
2.  Jendrossek, D. and Reinhardt, S. Sequence analysis of a gene product synthesized by Xanthomonas sp. during growth on natural rubber latex. FEMS Microbiol. Lett. 224 (2003) 61–65. [PMID: 12855168]
3.  Braaz, R., Fischer, P. and Jendrossek, D. Novel type of heme-dependent oxygenase catalyzes oxidative cleavage of rubber (poly-cis-1,4-isoprene). Appl. Environ. Microbiol. 70 (2004) 7388–7395. [PMID: 15574940]
4.  Braaz, R., Armbruster, W. and Jendrossek, D. Heme-dependent rubber oxygenase RoxA of Xanthomonas sp. cleaves the carbon backbone of poly(cis-1,4-Isoprene) by a dioxygenase mechanism. Appl. Environ. Microbiol. 71 (2005) 2473–2478. [PMID: 15870336]
5.  Seidel, J., Schmitt, G., Hoffmann, M., Jendrossek, D. and Einsle, O. Structure of the processive rubber oxygenase RoxA from Xanthomonas sp. Proc. Natl. Acad. Sci. USA 110 (2013) 13833–13838. [PMID: 23922395]
6.  Birke, J. and Jendrossek, D. Rubber oxygenase and latex clearing protein cleave rubber to different products and use different cleavage mechanisms. Appl. Environ. Microbiol. 80 (2014) 5012–5020. [PMID: 24907333]
7.  Birke, J., Röther, W. and Jendrossek, D. RoxB is a novel type of rubber oxygenase that combines properties of rubber oxygenase RoxA and latex clearing protein (Lcp). Appl. Environ. Microbiol. 83 (2017) e00721-17. [PMID: 28500046]
[EC created 2018]