Cyclodextrins as molecular tools to investigate the surface properties of potato 5-lipoxygenase.

The behavior of potato 5-lipoxygenase acting on both monomeric and aggregated linoleic acid has been studied. While the substrate preparation was transparent, lipoxygenase activity was determined by means of a spectrophotometric method, which was not useful to determine the activity in turbid samples. In the latter case a polarographic method was used. Cyclodextrins were used in order to increase the range of monomeric, and thus transparent, linoleic acid. This clearly revealed that potato 5-lipoxygenase can be saturated by linoleic acid monomers but when aggregates are formed at higher linoleic acid concentration, activity raises and stabilizes in a new saturation level. This was interpreted as an activation of lipoxygenase induced by the aggregation of its substrate, linoleic acid. Kinetic parameters were determined in each region — monomeric and aggregate — and are consistent with the surface activation hypothesis. [ABSTRACT FROM AUTHOR]