Shigeki Sakakibara

Induction and activation of cysteine oxidase of rat liver II. The measurement of cysteine metabolism in vivo and the activation of in vivo activity of cysteine oxidase

Abstract 1. 1. The incorporation of 14 C into expired CO 2 from DL -[3- 14 C]cysteine injected intraperitoneally into rats was slightly decreased by a loading dose of D -cysteine, whereas either the incorporation from DL -[1- 14 C]cysteine or L -[U- 14 C]-cysteine was unaffected by this loading. 2. 2. The incorporation of 14 C into CO 2 from DL [1- 14 C]cysteine or L -[U- 14 C]-cysteine was remarkably elavated by L -cysteine loading. 3. 3. Hepatic cysteine oxidase activity was markedly induced by L -cysteine injection but cysteine desulfhydrase activity was not affected. 4. 4. The expected maximum 14 CO 2 expirations expressed as C max and the C max half-times for DL -[1- 14 C]cysteine, DL -[3- 14 C]cysteine and L -[U- 14 C]cysteine injected were calculated from the kinetics of 14 CO 2 expiration as a function of time. 5. 5. The metabolic distributions of L -cysteine catabolism was calculated from these C max values; L -cysteine is metabolized 31% via the pyruvate pathway and 69% via the taurine pathway. 6. 6. Urinary excretion of 35 S from L -[ 35 S]cysteine injected was also examined. 7. 7. The facts presented in this paper strongly suggest that the degradation of L -cysteine is metabolized mainly through cysteine sulfinate, and therefore the incorporation of 14 CO 2 into expired CO 2 from L -[U- 14 C]cysteine is a reflection of the in vivo activity of cysteine oxidase and that the in vivo activity of cysteine oxidase was markedly enhanced by L -cysteine loading but not by D -cysteine loading.

Induction and activation of cysteine oxidase of rat liver: I. The effects of cysteine, hydrocortisone and nicotinamide injection on hepatic cysteine oxidase and tyrosine transaminase activities of intact and adrenalectomized rats

Abstract 1. 1. The greatest increase in hepatic cysteine oxidase activity was observed in intact rats which received cysteine, but the increase in tyrosine transaminase activity mediated by cysteine was only one-half of that produced with nicotinamide or hydrocortisone. 2. 2. The decline of the elevated enzymic activity of either cysteine oxidase or tyrosine transaminase was delayed when these enzymes were induced by nicotinamide in intact rats. 3. 3. An additive increase in cystein oxidase activity in the intact rat was obtained by the simultaneous injection of nicotinamide with cysteine and of nicotinamide with hydrocortisone but not of cysteine with hydrocortisone. 4. 4. Hepatic cysteine oxidase and tyrosine transaminase activities in adrenalectomized rats were significantly increased after injection of hydrocortisone but not by cystein. Nicotinamide did produce a marked increase in tyrosine transaminase activity in adrenalectomized rats, while cysteine oxidase activity did not increase with either nicotinamide or cysteine. The hydrocortisone-mediated induction of hepatic cysteine oxidase activity was markedly enhanced by simultaneous injection of cysteine, but in the case of hepatic tyrosine transaminase activity, the hydrocortisone-mediated induction was not affected by cysteine injection. 5. 5. Cysteine-mediated induction of hepatic cysteine oxidase was partially inhibited by the simultaneous injection of cycloheximide, whereas hydrocortisone- and nicotinamide-mediated inductions were completely inhibited by cycloheximide.

Purification and some properties of rat liver cysteine oxidase (cysteine dioxygenase)

Cysteine oxidase (cysteine dioxygenase, EC 1.13.11.20) was purified approximately 1000-fold from rat liver. The purified enzyme (protein-B) was obtained as an inactive form, which was activated by anaerobic preincubation with L-cysteine. The active form of protein-B was inactivated during aerobic incubation to produce cysteine sulfinate. This inactivation of protein-B was protected by a distinct protein in rat liver cytoplasm, namely stabilizing protein (protein-A). The Ka and Km values for L-cysteine were 0.8-10(-3) M and 1.3-10(-3) M respectively. The enzyme was strongly inhibited by Cu+ and/or Fe2+ chelating agents but not by Cu2+ chelating agent. The optimum pH of enzyme reaction was 8.5-9.5 while that of enzyme activation was 6.8-9.5, with a broad peak.

Two components of cysteine oxidase in rat liver

Abstract Purified cysteine oxidase in rat liver is composed of two distinct proteins. These proteins are able to be fractionated by DEAE-cellulose column chromatography. It appears that one of them is a catalytic protein named protein-B having tightly bound iron as a prosthetic group, while the other is either a modifier or activating protein named protein-A. Protein-B is found to exist in both an active and an inactive form. Inactive protein-B is activated by incubation with substrate cysteine under anaerobic condition. Activated protein-B alone exhibited an extremely low catalytic activity but in the presence of protein-A remarkable increase in activity was observed.

Cysteine metabolism in vivo of vitamin B6-deficient rats.

The expirations of 14CO2 from DL-[1-14C]-, DL-[3-14C]- and L-[U-14C] cysteine used as isotopic tracers were estimated in order to determine the in vivo metabolic distribution of L-cysteine in pyridoxine deficient rats. The expired 14CO2 from L-[U-14C] cysteine was increased by pyridoxine deficiency. The loading of non-physiological dose of L-cysteine resulted in remarkable increase in the expiration of 14CO2 from each tracer in deficient rats as well as in controls. The in vivo metabolic distributions of L-cysteine were calculated from the expired 14CO2 from these isotopic tracers. The in vivo metabolic distribution of L-cysteine calculated showed that the remarkable lesion in taurine pathway occurred in pyridoxine deficient rats, and when non-physiological dose of L-cysteine was loaded the catabolism of L-cysteine of controls was markedly increased in either pyruvate or taurine pathway, whereas the L-cysteine catabolism in deficient rats was increased only in pyruvate but not in taurine pathway. The urinary excretions of 35S-labeled metabolites such as sulfate or taurine were also examined in deficient and control rats.

The effect of pyrazines on the metabolism of tryptophan and nicotinamide adenine dinucleotide in the rat Evidence of the formation of a potent inhibitor of aminocarboxy-muconate-semialdehyde decarboxylase from pyrazinamide

The intraperitoneal or oral administration of pyrazinamide and pyrazinoic acid (pyrazine 2-carboxylic acid) resulted in a marked increase of the NAD content in rat liver. The injections of pyrazine and pyrazine 2,3-dicarboxylic acid exhibited no significant effect on the hepatic NAD content. The boiled extract obtained from liver and kidney of rat injected with either pyrazinamide or pyrazinoic acid exhibited a potent inhibitory effect on the aminocarboxymuconate-semialdehyde decarboxylase (EC 4.1.1.45) activity in either lier or kidney, although pyrazinamide or pyrazinoic acid per se did not inhibit the enzyme activity. The unknown inhibitor of aminocarboxymuconate-semialdehyde decarboxylase was dialysable and heat-stable, and mostly excreted in urine by 6 and 12 h after injected of pyrazinoic acid and pyrazinamide, respectively. Pyrazine 2,3-dicarboxylic acid, pyrazine, nicotinamide, nicotinic acid, tryptophan, anthranilic acid, 5-hydroxyanthranilic acid and quinolinic acid exhibited no significant effect on the aminocarboxymuconate-semialdehyde decarboxylase activity in liver and kidney at the concentration of 1 mM in the reaction mixture. The expired 14CO2 from L-[benzen ring-U-14C]tryptophan was markedly decreased by the pyrazinamide injection, while the urinary excretion of 14C-labeled metabolites from L-tryptophan, mainly quinolinic acid, was markedly increased. These results suggest that the glutarate pathway of L-tryptophan was strongly inhibited by the inhibitor produced after the administration of pyrazinoic acid and pyrazinamide. Pyrazinamide but not pyrazinoic acid also exhibited a significant inhibition of the nuclear enzyme poly(ADP-ribose) synthetase in rat liver.

The protective effect of polyriboinosinic acid-polyribocytidylic acid against the occurrence of galactosamine-induced liver cell injury in rat

A marked increase of serum transaminase activities, histological changes of livers similar to those seen in viral hepatitis in man, and inhibition of hepatic protein synthesis were observed in rats following a single injection of D-galactosamine-HCl. These galactosamine-induced phenomena were prevented by the pretreatment of polyriboinosinic acidpolyribocytidylic acid 24 h before the galactosamine administration.

Genetic polymorphism of mitochondrial glutamate-oxaloacetate transaminase in Japanese

SummaryA survey of a number of unselected sera indicated the presence of a variant allele of mitochondrial glutamate-oxaloacetate transaminase (Gotm2) in Japanese with appreciable frequency, which was confirmed in white blood cells. The mode of an autosomal codominant inheritance was confirmed by two independent family studies.

Intensification of galactosamine hepatotoxicity by polyriboinosinic acid-polyribocytidylic acid

The effects of polyriboinosinic acid-polyribocytidylic acid (poly IC) on galactosamine-induced liver cell injury in rats were studied. Treatment of rats with D-galactosamine-HC1 (400 mg/kg) increased their serum glutamate-oxaloacetate transaminase (E.C.2.6.1.1, GOT) activities, indicating that hepatocyte injury was induced by galactosamine. Rapid and intense elevations of serum GOT activities were observed when galactosamine (200 mg/kg) was administered simultaneously with poly IC (10 mg/kg) but not with poly I or poly C. Acute increase in serum GOT activities caused by the simultaneous administration of poly IC and galactosamine was prevented by the simultaneous administration of uridine (1 g/kg), which is known to inhibit the early biochemical alterations caused by the amino sugar in the hepatocyte. These findings suggest that poly IC intensifies the hepatotoxic effect of galactosamine in rats. This poly IC-induced sensitization was inhibited by pretreatment with poly IC (10 mg/kg) itself, when injected 24 hr before the administration of the hepatotoxin together with poly IC.