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Inactivation of soybean lipoxygenase 1 by 12-iodo-cis-9-octadecenoic acid
S A Rotenberg1, A M Grandizio, A T Selzer
1Department of Chemistry, Bucknell University, Lewisburg, Pennsylvania 17837.
Abstract:
12-Iodo-cis-9-octadecenoic acid (12-IODE) is a time-dependent, irreversible inactivator of soybean lipoxygenase 1. The rate of inactivation is independent of 12-IODE concentration above 20 microM and is half-maximal at about 4 microM. Inactivation by 12-IODE requires lipid hydroperoxide, which must be present even after the initial oxidation of the iron in the enzyme from ferrous to ferric. Inactivation by 12-IODE is also dependent on O2. These findings suggest that 12-IODE is converted by the enzyme into a more reactive species, which is responsible for inactivation. No inactivation has been detected with 12-iodooctadecanoic acid, 12-bromo-cis-9-octadecenoic acid, 12-iodo-trans-9-octadecenoic acid, or a mixture of stereoisomers of 9,11-octadecadienoic acid.