Differential effects of polylysine on NADH-linked electron transfer in corn root plasma membrane vesicles
1994
Tu, S.I. | Brauer, D. | Xu, Yi
The effects of polylysine on the electron transfer from NADH to cytochrome c and ferricyanide in corn root plasma membrane vesicles were investigated. The presence of polylysine decreased the reduction rate of cytochrome c but slightly stimulated the rate of ferricyanide reduction in a pH 7.5 medium of low ionic strength. An increase in ionic strength eliminated the effects of polylysine on ferricyanide reduction but not the inhibition of cytochrome c reduction. Kinetic analyses indicated that in high ionic strength medium, polylysine inhibition appeared to assume a competitive model suggesting its binding to cytochrome c reduction site. In low ionic strength medium, a complex inhibition was observed. A study on the inhibitory efficiency of different size polylysines suggested that the reduction site of cytochrome c may best fit a polylysine with molecular weight close to 25,000. The results support the notion that the electron transfer from NADH to these two acceptors may involve two separated enzymes or two different sites along an electron transfer chain in the plasma membrane.
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