CIRCULAR-DICHROISM OF LIPOXYGENASE-1 FROM SOYBEANS

The circular dichroism spectra of the three forms of lipoxygenase-1 from soybeans show characteristic differences in the region between 300 and 600 nm. Native lipoxygenase-1 only shows a negative dichroic band around 330 nm. Yellow lipoxygenase-1, obtained by addition of an equimolar amount of 13-l-hydroperoxylinoleic acid to the native enzyme, shows a positive Cotton effect at 425 nm, while the negative band at 330 nm has increased in intensity. The blue enzyme, representing a complex of yellow enzyme with 13-l-hydro-eroxylinoleic acid exhibits a negative dichroic band at 580 nm and positive bands at 410 and 391 nm. The near-ultraviolet CD spectra of the three forms of lipoxygenase are very similar, showing several well resolved positive dichroic bands at 0°C. Using the method of Chen et al. (Chen, Y.-H., Yang, J.T. and Martinez, H.M. (1972) Biochemistry 11, 4120-4131) the contents of α-helix, β- and unordered form of native lipoxygenase-1 were estimated to be 34, 27 and 39% respectively. © 1979.