A functional role identified for conserved charged residues at the active site entrance of lipoxygenase with double specificity

•Olive LOX1 active site entrance is surrounded by conserved positively charged residues.•Substitution of R265, R268 and K283 by glutamine has an effect on kinetic parameters.•These residues may interact with the substrate carboxylate.•K283 could play a more important role attributable to its position on α2 helix.•The role of these residues may be extended to all plant LOXs with double specificity.