Heat denaturation of bovine liver glutamate dehydrogenase

Heat denaturation of bovine liver glutamate dehydrogenase occurred at 47 degrees with loss of enzyme activity and formation of inactive, insoluble protein. Fractional loss of catalytic activity coincided with alteration in protein fluorescence and solubility for a corresponding percentage of protein molecules. Operationally, at 50% denaturation, one-half of the total population of enzyme molecules is fully active catalytically and soluble and the other half of the protein molecule population is completely inactive catalytically and insoluble.

Ethidium bromide inhibits mitochondrial phosphorylating oxidation

Ethidium bromide, in addition to combination with mitochondrial nucleic acids, is a phosphorylation inhibitor during glutamate and succinate respiration by mitochondria. Exhaustive washing of ethidium bromide-treated mitochondria did not relieve the inhibition nor significantly decrease the amount of bound dye. Dialysis against a cation exchange resin at 3 degrees for 17 hr removed about 97% of bound dye. This restored phosphorylating capacity to that of untreated mitochondria which had also been dialyzed against the resin. Since state 3 respiration was diminished and state 4 was unaffected by the presence of the acridine dye, and since neither swelling of mitochondria nor release of latent ATPase was observed, then ethidium bromide was not an electron transport inhibitor nor an uncoupler of oxidative phosphorylation. Inhibition of metabolic processes by ethidium bromide may be due in part to depressed generation of mitochondrial ATP.

The arthritogenic effect of indole, skatole and other tryptophan metabolites in rabbits

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