Endogenous factor in rat liver that converts tyrosine aminotransferase form III to form I: A rapid assay of this converting factor

Boctor, Amal M.; Grossman, Albert

doi:10.1016/0003-2697(78)90807-2

Cited by 7 publications

(1 citation statement)

References 8 publications

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“…Since the inactivating factor appeared to be localized in microsomal particles, in all further inactivation experiments nuclei, mitochondria and lysosomes were eliminated from the incubation medium to minimize possible interfering effects caused by the release of cathepsins and converting factor from lysosomes (Auricchio et al, 1972;Boctor & Grossman, 1978;Gohda & Pitot, 1980).…”

Section: Resultsmentioning

confidence: 99%

Effect of physiological reducing compounds on the inactivation of tyrosine aminotransferase from guinea-pig liver*

Cola¹,

Federici²

1982

Biochemical Journal

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1. Tyrosine aminotransferase from guinea-pig liver is inactivated at neutral pH by a factor localized in the microsomal fraction. The inactivation, independent of exogenous L-cysteine, is rapidly reversed by addition of dithiothreitol. 2. The effects of physiological reducing agents on the enzyme inactivation were investigated. L-Cysteine and L-cysteamine enhance the inactivation rate of the enzyme in the presence of microsomal membranes, and also they are able to bring about the loss in enzyme activity independently of microsomal action. Reduced glutathione, at physiological concentration, and NADPH decrease the inactivation rate. Other physiological reducing compounds, as well as oxidized glutathione and NADP+, are without effect. 3. Neither reduced glutathione nor NADPH, unlike dithiothreitol and mercaptoethanol, is able to restore the activity of partially inactivated tyrosine aminotransferase. 4. It is proposed that the intracellular concentration of reduced glutathione might modulate the rate of inactivation of the enzyme in vivo.

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Section: Resultsmentioning

confidence: 99%