Hepatic Cysteine Dioxygenase Activity and Sulfur Amino Acid Metabolism in Rats: Possible Indicators in the Evaluation of Protein Quality

Abstract

Experiments were carried out to examine the possibility that the sulfur amino acid metabolism of rats may be an indicator of the nutritional value of dietary protein. Rats were fed diets containing 8, 16 or 24% of gluten, soy protein or casein for 3 wk. Hepatic cysteine dioxygenase activity, hepatic concentration of glutathione, cysteine and taurine and urinary taurine were examined. In addition, the sulfur amino acid metabolism of rats fed these diets fortified with the appropriate first limiting amino acid for 7 d was also examined. High urinary taurine excretion was observed in the three gluten groups, whereas very low urinary taurine excretion was observed with up to 24% soy protein or up to 16% casein. The hepatic hepatic cysteine dioxygenase activities of the gluten diet groups were higher than those of corresponding soy protein or casein diet groups, except that of rats fed the 24% casein diet. The hepatic concentrations of both glutathione and cysteine in gluten diet groups were also higher than those of corresponding soy protein or casein diet groups, except 24% soy protein and 16 and 24% casein diet groups. In rats fed the casein or soy protein diets urinary taurine excretion and hepatic cysteine dioxygenase activity increased with increasing methionine supplementation, the first limiting amino acid. Conversely, in rats fed the gluten diet both urinary taurine excretion and hepatic cysteine dioxygenase activity decreased with increasing lysine supplementation, the first limiting amino acid. These findings suggest that urinary taurine excretion and hepatic cysteine dioxygenase activity may be useful as sensitive indicators of the nutritional value of dietary protein.

Growing Rats Respond to a Sulfur Amino Acid–Deficient Diet by Phosphorylation of the α Subunit of Eukaryotic Initiation Factor 2 Heterotrimeric Complex and Induction of Adaptive Components of the Integrated Stress Response

“…Thus, our results extend the observations in mice to the situation in which the diet is only partially deficient in an essential amino acid (i.e. SAA), to an amino acid pattern that is more representative of that in diets consumed by humans and animals, and to a diet that has been shown to support both growth and longevity (29)(30)(31).…”

“…A number of studies have shown an association of eIF2a phosphorylation with induction of a state of stress resistance in cells (29,30). This study now shows that modest SAA restriction can induce the ISR in liver of intact growing rats.…”

Total 4EBP1 Is Elevated in Liver of Rats in Response to Low Sulfur Amino Acid Intake

“…Diets were prepared by Dyets Inc. (Bethlehem, PA, USA). Sulfur amino acid levels were based on previous rat studies that demonstrated that 2.3 g methionine is adequate to meet the absolute requirement of growing rats for methionine (i.e., the requirement for methionine when cyst(e)ine is not limited in the diet) [29, 30]. For diet preparation, the powdered diets were mixed with an equal volume (1 L/kg diet) of hot agar solution (3 g/L), and the mixture was cooled at room temperature, refrigerated, and cut into cubes for feeding.…”

Intraperitoneal injection of sulfur amino acids enhance the hepatic cysteine dioxygenase activity in rainbow trout (Oncorhynchus mykiss)

“…It is accepted that L-cysteinesulfinate is a key intermediate product both in the catabolic pathway to form pyruvate and sulfate, and in taurine biosynthesis pathway from L-cysteine in mammals as shown in Figure 1 (Yamaguchi and Hosokawa 1987a;Yamaguchi 1990). Therefore, cysteine dioxygenase (CDO) [EC 1.13.11.20] which catalyzes the oxygenation of L-cysteine to form Lcysteine sulfinate has been considered to participate in the regulation of sulfur amino acid metabolism in mammals (Daniels and Stipanuk 1982;Hosokawa et al 1988). Recently, we have observed that the CDO is present in the liver of rainbow trout, and that this enzyme was induced both by dietary supplementation of an excess amount of methionine and cystine, and by high protein diet as well (Yokoyama and Nakazoe 1989;Yokoyama et al 1994).…”