Sheep uterus dual lipoxygenase in the synthesis of 14,15-leukotrienes.
Lipoxygenase was purified to homogeneity from sheep uterus cytosol using a combination of ion exchangers, ammonium sulfate fractionation, and gel filtration. The purified enzyme was found to be a homodimeric protein with monomer molecular weight of 66 kDa. When incubated with arachidonic acid, the enzyme showed two lipoxygenase activities producing both 12- and 15-HPETEs at the optimum pH of 5.5. The relative concentration of 12- and 15-HETEs, however, changed with the pH of the reaction, 12-HETE being higher in the alkaline range and 15-HETE being higher in the acidic range. Furthermore the enzyme showed the expected dual lipoxygenase based 14,15-LTA4 synthase activity as evidenced by the formation of 8,15-diHETEs, the hydrolysis products of 14,15-LTA4. Isolation of 14,15-LTC4 from the homogenates of sheep uterus gave further evidence on the formation of leukotrienes. This is the first report of the formation of 14,15-series leukotrienes in mammalian reproductive tissue.
Sailesh
S
S
School of Life Sciences, University of Hyderabad, India.
Kumar
Y V
YV
Prasad
M
M
Reddanna
P
P
D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D005260:Female; D015289:Leukotrienes / Q000096:biosynthesis* / Q000737:chemistry; D008084:Lipoxygenase / Q000737:chemistry / Q000378:metabolism*; D013058:Mass Spectrometry; D008970:Molecular Weight; D012756:Sheep; D014599:Uterus / Q000201:enzymology*
D015289:Leukotrienes; D008084:Lipoxygenase; D001094:Arachidonate 5-Lipoxygenase