S. Sailesh et al., SHEEP UTERUS DUAL LIPOXYGENASE IN THE SYNTHESIS OF 14,15-LEUKOTRIENES, Archives of biochemistry and biophysics, 315(2), 1994, pp. 362-368
Lipoxygenase was purified to homogeneity from sheep uterus cytosol usi
ng a combination of ion exchangers, ammonium sulfate fractionation, an
d gel filtration. The purified enzyme was found to be a homodimeric pr
otein with monomer molecular weight of 66 kDa. When incubated with ara
chidonic acid, the enzyme showed two lipoxygenase activities producing
both 12- and 15-HPETEs at the optimum pH of 5.5. The relative concent
ration of 12- and 15-HETEs, however, changed with the pH of the reacti
on, 12-HETE being higher in the alkaline range and 15-HETE being highe
r in the acidic range. Furthermore the enzyme showed the expected dual
lipoxygenase based 14,15-LTA(4) synthase activity as evidenced by the
formation of 8,15-diHETEs, the hydrolysis products of 14,15-LTA(4). I
solation of 14,15-LTC(4) from the homogenates of sheep uterus gave fur
ther evidence on the formation of leukotrienes. This is the first repo
rt of the formation of 14,15-series leukotrienes in mammalian reproduc
tive tissue. (C) 1994 Academic Press, Inc.