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Tomato CYP74C3 is a Multifunctional Enzyme not only Synthesizing Allene Oxide but also Catalyzing its Hydrolysis and Cyclization
Author(s) -
Grechkin Alexander N.,
Mukhtarova Lucia S.,
Latypova Larisa R.,
Gogolev Yuri,
Toporkova Yana Y.,
Hamberg Mats
Publication year - 2008
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.200800331
Subject(s) - allene , cyclopentenone , chemistry , yield (engineering) , linoleic acid , methanol , oxide , hydrolysis , stereochemistry , organic chemistry , catalysis , fatty acid , materials science , metallurgy
The mechanism of the recombinant tomato allene oxide synthase (LeAOS3, CYP74C3) was studied. Incubations of linoleic acid (9 S )‐hydroperoxide with dilute suspensions of LeAOS3 (10–20 s, 0 °C) yield mostly the expected allene oxide (12 Z) ‐9,10‐epoxy‐10,12‐octadecadienoic acid (9,10‐EOD), which was detected as its methanol‐trapping product. In contrast, the relative yield of 9,10‐EOD progressively decreased when the incubations were performed with fourfold, tenfold, or 80‐fold larger amounts of LeAOS3, while α‐ketol and the cyclopentenone rac ‐ cis ‐10‐oxo‐11‐phytoenoic acid (10‐oxo‐PEA) became the predominant products. Both the α‐ketol and 10‐oxo‐PEA were also produced when LeAOS3 was exposed to preformed 9,10‐EOD, which was generated by maize allene oxide synthase (CYP74A). LeAOS3 also converted linoleic acid (13 S )‐hydroperoxide into the corresponding allene oxide, but with about tenfold lower yield of cyclopentenone. The results indicate that in contrast to the ordinary allene oxide synthases (CYP74A subfamily), LeAOS3 (CYP74C subfamily) is a multifunctional enzyme, catalyzing not only the synthesis, but also the hydrolysis and cyclization of allene oxide.