Unknown

Dataset Information

0

Lipoxin synthase activity of human platelet 12-lipoxygenase.


ABSTRACT: Human platelets and megacaryocytes generate lipoxins from exogenous leukotriene A4 (LTA4). We examined the role of human 12-lipoxygenase (12-LO) in lipoxin generation with recombinant histidine-tagged human platelet enzyme (6His-12-LO), partially purified 12-LO from human platelets (HPL 12-LO) and, for the purposes of direct comparison, permeabilized platelets. Recombinant and HPL 12-LO catalysed the conversion of intact LTA4 into both lipoxin A4 (LXA4) and lipoxin B4 (LXB4). In contrast, only negligible quantities of LXA4 were generated when recombinant 12-LO was incubated with the non-enzymic hydrolysis products of LTA4.6His-12-LO also converted a non-allylic epoxide, 5(6)-epoxy-(8Z,11Z,14Z)-eicosatrienoic acid. The apparent Km and Vmax. for lipoxin synthase activity of 6His-12-LO were estimated to be 7.9 +/- 0.8 microM and 24.5 +/- 2.5 nmol/min per mg respectively, and the LXB4 synthase activity of this enzyme was selectively regulated by suicide inactivation. Aspirin gave a 2-fold increase in lipoxin formation by platelets but did not enhance the conversion of LTA4 by the recombinant 12-LO. These results provide direct evidence for LXA4 and LXB4 synthase activity of human platelet 12-LO. Moreover, they suggest that 12-LO is a dual-function enzyme that carries both oxygenase and lipoxin synthase activity.

SUBMITTER: Romano M 

PROVIDER: S-EPMC1137664 | biostudies-other | 1993 Nov

REPOSITORIES: biostudies-other

Similar Datasets

| S-EPMC7270142 | biostudies-literature
| S-EPMC3494251 | biostudies-literature
| S-EPMC3286293 | biostudies-literature
| S-EPMC3150642 | biostudies-literature
| S-EPMC3960303 | biostudies-literature
| S-EPMC19701 | biostudies-literature
| S-EPMC7270147 | biostudies-literature
| S-EPMC6484126 | biostudies-literature
| S-EPMC4500271 | biostudies-literature
| S-EPMC54382 | biostudies-other