The synthesis of hippurate from benzoate and glycine by rat liver mitochondria. Submitochondrial localization and kinetics

Abstract

1. Rat liver mitochondria make hippurate at up to 4 nmol/min per mg of protein. The rate of synthesis supported by oxidation of glutamate with exogenous Pi present is identical with that supported by ATP plus oligomycin. Lower rates were obtained with other respiratory substrates, and when glutamate was used without Pi. 2. A matrix localization for hippurate synthesis is indicated by the latency of benzoyl-CoA synthetase and glycine N-acyltransferase to their extramitochondrial substrates, failure of exogenous benzoyl-CoA to inhibit incorporation of [14C]hippurate and inhibition of hippurate synthesis supported by ATP, but not glutamate, by carboxyatractyloside. 3. The relative activities of the individual enzymes and the mitochondrial content of benzoyl-CoA in the presence and absence of glycine suggest that hippurate synthesis is rate-limited by formation of benzoyl-CoA. 4. The increases in rates of ATP hydrolysis and of O2 consumption on the addition of benzoate and glycine were in good agreement with those required to support hippurate synthesis. The increase in respiration indicates that State-4 respiration [Chance & Williams (1957) Adv. Enzymol 17, 65-134] is not used, with these conditions, for ATP synthesis.

Benzoate and Sorbate Salts: A Systematic Review of the Potential Hazards of These Invaluable Preservatives and the Expanding Spectrum of Clinical Uses for Sodium Benzoate

“…The branched-chain valproate (Figure 1) mainly undergoes β-oxidation using the isoleucine catabolic pathway and enzymes. Benzoate accumulates in the matrix of liver and kidney mitochondria to about 50-fold over its extra-mitochondrial concentration (Gatley and Sherratt 1977), where it is conjugated with glycine-the most abundant free amino acid in the adult human liver. It is thereby converted to hippurate, a compound that can be efficiently removed from the body by the kidneys (Gatley and Sherratt 1977;Beyoglu and Idle 2012).…”

“…Benzoate accumulates in the matrix of liver and kidney mitochondria to about 50-fold over its extra-mitochondrial concentration (Gatley and Sherratt 1977), where it is conjugated with glycine-the most abundant free amino acid in the adult human liver. It is thereby converted to hippurate, a compound that can be efficiently removed from the body by the kidneys (Gatley and Sherratt 1977;Beyoglu and Idle 2012). This process acts not only as a mechanism of detoxification, increasing the water solubility of this organic acid in order to facilitate its urinary excretion, but also as a means of regulating systemic levels of amino acids utilized as neurotransmitters in the central nervous system (Badenhorst and others 2014).…”

Moment Analysis of Metabolic Heterogeneity: Conjugation of Benzoate with Glycine in Rat Liver Studied by Multiple Indicator Dilution Technique

“…1A). However, with the present precursor-product pair, benzoate and hippurate, glycine conjugation occurs within the mitochondria (Gatley and Sherratt, 1977), evoking consideration of an extra pool (Fig. 1B).…”

Cytotoxicities of sodium benzoate in primary culture of hepatocytes from adult rat liver.

“…No report on functional disturbance of the liver due to BA-Na has been reported. An influence of BA-Na on mitochondrial enzymes, however, has been reported (Gatley and Sherratt 1977). In the present study, the hepatic toxicity of BA-Na was evaluated in vitro using primary culture of hepatocytes.…”