Lipoxygenase (LOX) are enzymes implicated in a broad range of inflammatory diseases, cancer, asthma and atherosclerosis. These diverse biological properties lead to the interesting target for the inhibition of this metabolic pathway of LOX. The drugs available in the market against LOX reported to have various side effects. To develop potent and selective therapeutic agents against LOX, it is essential to have the knowledge of its active site. Due to the lack of structural data of human LOX, researchers are using soybean LOX (sLOX) because of their availability and similarities in the active site structure. Based on the crystal structure of sLOX-3 and its complex with known inhibitors, we have designed a tripeptide, FWY which strongly inhibits sLOX-3 activity. The inhibition by peptide has been tested with purified sLOX-3 and with LOX present in blood serum of breast cancer patients in the presence of substrate linoleic acid and arachidonic acid respectively. The dissociation constant (K(D)) of the peptide with sLOX-3 as determined by Surface Plasmon Resonance (SPR) was 3.59x10(-9) M. The kinetic constant (K(i)) and IC(50), as determined biochemical methods were 7.41x10(-8) M and 0.15x10(-6) M respectively.