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Kinetics of the interaction between bovine heart mitochondrial F(1) and its inhibitors
Abstract
The kinetics of bovine heart mitochondrial F$\sb1$ and F$\sb1$-inhibitor protein were examined employing spectroscopic enzyme activity assays. Results showed that F$\sb1$-inhibitor protein is a slow, tight binding noncompetitive inhibitor of F$\sb1$. Kinetic equations describing the interaction were derived and the inhibition constants were found to be in the range of 10$\sp{-7}$M for both K$\sb1$ and $\alpha$K$\sb1$. The kinetics of citreoviridin, a polyene neurotoxin, which inhibits soluble and membrane bound F$\sb1$, were examined and the reasons for citreoviridin binding were investigated. From the results of the study, it was concluded that citreoviridin is a very potent, stereospecific, uncompetitive inhibitor of ATP hydrolysis catalyzed by soluble or membrane bound F$\sb1$. Citreoviridin is also a stereospecific competitive inhibitor of ATP synthesis catalyzed by membrane bound F$\sb1$. Inhibition constants for citreoviridin were found to be around 5$\mu$M for ATP hydrolysis for both soluble and membrane bound F$\sb1$. The inhibition constant for ATP synthesis was much lower, 0.12$\mu$M. Isocitreoviridin, which is a photoisomer of citreoviridin, had no effect on ATP hydrolysis or on ATP synthesis catalyzed by soluble and membrane bound F$\sb1$. From the kinetics studies, performed using nucleotides, nucleotide analogs and 8-substituted nucleotide anologs evidence was obtained that citreoviridin binds regulatory nucleotide binding sites on F$\sb1$.
Subject Area
Biochemistry
Recommended Citation
Sayood, Sefika Fusun, "Kinetics of the interaction between bovine heart mitochondrial F(1) and its inhibitors" (1988). ETD collection for University of Nebraska-Lincoln. AAI8824951.
https://digitalcommons.unl.edu/dissertations/AAI8824951