Optimizing arachidonate lipoxygenating species for biotechnological
applications
Current knowledge on the structural determinants of the active site of plant and
mammalian LOXs was summarized in Section 15.1.3. This information may be help-
ful to design stable LOX species exhibiting a desired positional specificity for bio-
technological application. Moreover, it may be possible to optimize the biochemical
properties of LOXs already being used for such purpose. The physiologically most
relevant mammalian LOX isoforms are the 5-LOXs, which catalyze the initial steps
in leukotriene biosynthesis. Leukotrienes are important mediators of hyperergic and
inflammation disease (Samuelsson et al., 1987) and inhibitors are already available
as anti-asthmatic drugs. Although mammalian 5-LOXs have been purified from nat-
ural and recombinant sources, the purified enzymes are unstable and difficult to
handle (Ford-Hutchinson et al., 1994). Moreover, they require a set of essential co-
factors such as Ca2+, ATP and phospholipid vesicles for maximal activity. To cir-
cumvent these problems several plant arachidonate 5-LOXs have been tested
whether they constitute as a suitable model for the physiologically more relevant
mammalian enzymes. Among plant 5-LOXs only the potato tuber enzyme converts
15.3 The structural bases of the positional specificity of LOXs 329
Figure 10. Straight-phase HPLC analysis of hydroxy polyenoic fatty acids formed from AA by the
potato tuber LOX and its V576F mutant.