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Location: Renewable Product Technology Research

Title: Thermostable Lipoxygenase, a Key Enzyme in the Conversion of Linoleic Acid into Thrihydroxy-octadecenoic Acid by Pseudomonas aeruginosa PR3

item Bae, Jae-han
item Hou, Ching
item Kim, Hak-ryul

Submitted to: Journal of Biotechnology and Bioprocess Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/30/2010
Publication Date: 1/30/2011
Citation: Bae, J., Hou, C.T., Kim, H. 2011. Thermostable lipoxygenase, a key enzyme in the conversion of linoleic acid into thrihydroxy-octadecenoic acid by Pseudomonas aeruginosa PR3. Journal of Biotechnology and Bioprocess Engineering. 15:1022-1030.

Interpretive Summary: Previously, we discovered a new microbial culture that produced a 7,10-dihydroxy-fatty acid from oleic acid and trihydroxy fatty acids from linoleic acid. Hydroxy fatty acids are useful as starting materials for the synthesis of specialty chemicals, special military nylon, plastisizers, coating materials, and possibly as physiologically active agents. Lipoxygenase (LOX) is an enzyme predicted to be involved in the conversion of linoleic acid by this strain. This information is critical to the understanding the pathway of hydroxyl fatty acid production by bioprocess. Herein we describe the purification and characterization of a novel thermostable LOX. Our study is the first report a novel thermostable LOX from this strain Pseudomonas strain. Our findings can facilitate the research on hydroxyl fatty acids production from vegetable oils by bioprocess and benefit researchers in the development of novel bioproducts from vegetable oils.

Technical Abstract: Lipoxygenases (LOX) constitute a family of lipid-peroxidizing enzymes catalyzing the oxidation of unsaturated fatty acid with (1Z,4Z)-pentadiene structural unit, leading to formation of the conjugated (Z,E)-hydroperoxydienoic acid. LOXs have been known to be widely distributed in plants and animals. Recently several microbial LOXs were reported to be involved in the production of hydroperoxy fatty acids. Among microorganisms known to produce hydroxy fatty acid, Pseudomonas aeruginosa PR3 had been studied to convert linoleic acid into trihydroxy fatty acids suggesting that a LOX was possibly involved in that process. Based on these reports, we tried to isolate a LOX from P. aeruginosa PR3 strain and firstly identified a novel thermostable lipoxygenase from P. aeruginosa PR3. The protein was purified with 34.3 of purification fold and 5.14 % of recovery. Km and Vmax values of the purified enzyme were 3.57 mM and 0.73 µmol •min**-1•mg**-1, respectively. Heat stability of the purified enzyme was unexpectedly high representing 90 minutes of LD50 of enzyme activity at 80 degree C although P. aeruginosa PR3 was a mesophilic bacterium. Substrate specificity of the purified enzyme was restricted only to the unsaturated fatty acids carrying (1Z,4Z)-pentadiene unit.