Oleyl Sulfate Reveals Allosteric Inhibition of Soybean Lipoxygenase-1 and Human 15-Lipoxygenase
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- 作者：Rakesh Mogul ; Eric Johansen ; and Theodore R. Holman
- 刊名：Biochemistry
- 出版年：2000
- 出版时间：April 25, 2000
- 年：2000
- 卷：39
- 期：16
- 页码：4801 - 4807
- 全文大小：184K
- 年卷期：v.39,no.16(April 25, 2000)
- ISSN：1520-4995
文摘
Inhibition of lipoxygenase (LO) is currently an important goal of biomedical research due toits critical role in asthma, atherosclerosis, and cancer regulation. Steady-state kinetic data indicate thatoleic acid (OA) is a simple competitive inhibitor for soybean lipoxygenase; however, kinetic isotopeeffect (KIE) data suggest a more complicated inhibitory mechanism. To investigate the inhibitory effectsof fatty acids on lipoxygenase more thoroughly, we have synthesized a novel inhibitor to lipoxygenase,(Z)-9-octadecenyl sulfate (oleyl sulfate, OS), which imparts kinetic properties that are inconsistent withsimple competitive inhibition for both SLO-1 and 15-HLO. The KIE exhibits a hyperbolic rise with additionof OS, indicating the formation of a catalytically active ternary complex with KD values of 0.6 ± 0.2 and0.4 ± 0.05 
M for SLO-1 and 15-HLO, respectively. The steady-state kinetics show that SLO-1 proceedsthrough a hyperbolic mixed-type inhibition pathway, where OS binding (Ki = 0.7 ± 0.3 M) causes anapproximate 4-fold increase in the Km(app) (
= 4.6 ± 0.5) and a decrease in the kcat by approximately15% (
= 0.85 ± 0.1). 15-HLO also exhibits a hyperbolic saturation of kcat/Km consistent with the observedrise in its KIE. Taken together, these findings indicate the presence of an allosteric site in both SLO-1and 15-HLO and suggest broad implications regarding the inhibition of LO and the treatment of LO-related diseases.
M for SLO-1 and 15-HLO, respectively. The steady-state kinetics show that SLO-1 proceedsthrough a hyperbolic mixed-type inhibition pathway, where OS binding (Ki = 0.7 ± 0.3 M) causes anapproximate 4-fold increase in the Km(app) ( = 4.6 ± 0.5) and a decrease in the kcat by approximately15% ( = 0.85 ± 0.1). 15-HLO also exhibits a hyperbolic saturation of kcat/Km consistent with the observedrise in its KIE. Taken together, these findings indicate the presence of an allosteric site in both SLO-1and 15-HLO and suggest broad implications regarding the inhibition of LO and the treatment of LO-related diseases.