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Small peptides from PEDF-R bind and inhibit lipoxygenase

Wednesday, November 06, 2013 — Poster Session I

4:00 p.m. – 6:00 p.m.

FAES Academic Center (Upper-Level Terrace)




  • P Subramanian
  • S. P. Becerra


Lipoxygenases (LOX) are enzymes responsible for the metabolism of arachidonic acid and other polyunsaturated fatty acids, thereby contributing to the generation of reactive oxygen species under oxidative stress. Pigment epithelium-derived factor receptor (PEDF-R), a PNPLA2 protein with phospholipase A2 (PLA2) activity, contains two peptide regions E5b (I193–L232) and P1 (T210-L249) that bind PEDF. Preliminary experiments showed that both peptides protected retinal pigment epithelial ARPE-19 cells from oxidative damage and also inhibited the coupled PLA/LOX enzymatic reaction. Here we investigated whether the above observation was due to direct binding and inhibition of lipoxygenase activity by the peptides. Peptide affinity chromatography demonstrated that soybean lipoxygenase V specifically bound to synthetic peptides E5b and P1 immobilized to agarose. Spectrophotometric assays with linoleic acid showed that both E5b and P1 inhibited the LOX activity in a concentration dependent manner. Inhibition of LOX activity was attenuated when the E5b peptide was captured with fluorescein-conjugated PEDF (Fl-PEDF), but it was not attenuated when Fl-BSA replaced Fl-PEDF. Thus, in addition to demonstrating that direct binding of the peptide inhibited LOX activity, our results support the idea that PEDF-R may bind and inhibit a mamalian lipoxygenase to protect the retinal pigment epithelium from oxidative stress.

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