Conformational changes of lipoxygenase (LOX) in modified environments. Contribution to the variation in specificity of soybean LOX type 1

The addition of water-soluble cosolvents in the reaction medium of type 1 soybean lipoxygenase can modify the selectivity of the enzyme in the hydroperoxide synthesis reaction. This also results in changes in secondary reactions such as carbonyl compound formation. The possibility of a conformational change of the enzyme due to variations in its microenvironment was considered. Using enzyme immobilization and laser visible Raman spectroscopy, both indirect and direct observations of such a protein conformational rearrangement are described. Subtle modifications in the secondary and/or tertiary structures, for example in microenvironments of Tyr and Trp residues, in orientations of lateral side chains were evidenced, and their importance to enzyme specificity is discussed.