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T Suga

Publications and source records attributed to T Suga.

At least 343 records · Page 19Linked to original sources
PubMed1980

Effects of fat content in the diet on hepatic peroxisomes of the rat.

Effects of fat content in the diet on rat liver peroxisomes was examined. In the livers of rats fed for one week on the high-fat diet containing 30% fat, the cyanide-insensitive palmitoyl-CoA oxidation was accelerated to eight times that of control and the enzymic activities of catalase, carnitine acetyltransferase and carnitine palmitoyltransferase were elevated by the factors of 1.3, 5 and 2, respectively. In contrast, the activities of D-amino acid oxidase in addition to the three enzymes mentioned above were all lowered by 20% when the animals were maintained on a fat-free diet for the same period of time. It appears that the high-fat diet-induced increase in the activity of carnitine palmitoyltransferase is a result of the raised activity of this enzyme in mitochondria only while the apparent high activity reflects stimulation of carnitine acetyltransferase in all the subcellular fractions. Another notable effect of the high-fat diet was a remarkable increase in the quantity of a peroxisome-associated polypeptide which was separable by sodium dodecyl sulfate polyacrylamide gel electrophoresis. It is noteworthy that this effect of the high-fat diet resemble that of clofibrate. If the diet was deprived of fat, however, this polypeptide species, with an estimated molecular weight of 80 000, decreased to a level slightly lower than normal. On the basis of the electron micrographic criteria, the high-fat diet provoked a marked proliferation of hepatic peroxisomes.

Animals↗
PubMed1980

Studies on peroxisomes. IX. Biochemical effects of simfibrate on precursor incorporation into polypeptide associated with peroxisome proliferation in rat liver.

Treatment with 1,3-propanediol-bis(2-p-chlorophenoxy-isobutyrate) (simfibrate), a hypolipidemic drug, showed little effect on liver weight and hepatic lipid level. When the effects of simfibrate on rat liver peroxisomal enzymes were examined, it was found that cyanide-insensitive fatty acyl-CoA oxidizing system and carnitine acetyltransferase activity increased from 0.38 U/g liver to 4.5 U/g liver and from 227 U/g liver to 6,450 U/g liver, respectively. The activity of D-amino acid oxidase decreased from 1.05 U/g liver to 0.39 U/g liver. Other peroxisomal enzymes including catalase and urate oxidase were not significantly changed by this drug. Of the protein components of the light mitochondrial fraction of simfibrate-treated rat liver, a polypeptide with a molecular weight of approximately 76,000, which has been suggested to be one of the peroxisomal proteins, increased in the treated rat liver (as estimated by sodium dodecylsulfate-polyacrylamide gel electrophoresis) and DL-[4,5-3H]leucine-incorporation into this particular component was also stimulated to a level about 3 times that of the control.

Animals↗
PubMed1980

Physiological role of peroxisomal beta-oxidation in liver of fasted rats.

In the livers of fasted rats, the activity of peroxisomal palmitocyl-CoA oxidation (NADH production) was increased more rapidly and markedly than that of mitochondrial carnitine palmitoyltransferase, which is the rate limiting enzyme of mitochondrial beta-oxidation. The peroxisomal oxidizing activity was about twice that of the control throughout the period of fasting (1-7 days). carnitine acetyltransferase activity was increased to a similar extent in both peroxisomes and mitochondria. A possible physiological role of liver peroxisomes may thus be as an effective supply of NADH2, acetyl residues and short and medium-length fatty acyl-CoA in the cells on the enhancement of peroxisomal beta-oxidation of the animals under starvation; these substances thus produced may be transported into the mitochondria as energy sources.

Acyl Coenzyme A↗
PubMed1980

Effect of pretreatment with butylated hydroxytoluene (BHT) on binding of 14C-BHT to lung microsomes.

The effect of pretreatment with BHT on the binding of 14C-BHT to lung microsomes was examined in vitro. The amount of radioactivity bound to microsomal macromolecules significantly decreased by pretreatment of rats with BHT. This decrease was accompanied by a decrement in the content of cytochrome P-450 and in BHT oxidase activity. Furthermore, the behaviour of these components was dependent upon the dose of BHT given. On the other hand, these three components were unchanged in phenobarbital-pretreated rats.

Animals↗
PubMed1979

Determination of the cross-points of rat liver peroxisomes, peroxisomal core and the core components by cross-partition.

The cross-points of rat liver peroxisomes, peroxisomal core and the core components were determined by means of cross-partition in two phase systems. The partitions were carried out in the systems containing 6% (w/w) Dextran T 500 and 6% (w/w) polyethyleneglycol 4000 in sodium salts. The same cross-point, pH 5.6, was obtained in peroxisomal marker enzymes in light mitochondrial fraction of liver homogenate, such as catalase, D-amino acid oxidase and urate oxidase. The cross-point as determined by cross-partition of purified peroxisomal core was 6.7. The cross-points of urate oxidase and framework protein fractions obtained by alkali treatment on the purified core were 7.8 and 4.2, respectively, and the ratio of the proteins of urate oxidase to framework protein was 2 : 1. The theoretical value of cross-point of the core calculated from from the relationship between the cross-point and protein ratio of each component of the core coincided with the experimental value obtained by this method.

Animals↗
PubMed1979

Effect of Triton WR-1339 on the rates of synthesis and degradation of hepatic catalase of rat.

The effect of Triton WR-1339 on the rates of synthesis and degradation of hepatic catalase was examined. Triton WR-1339 was injected intraperitoneally into rats at a dose of 200 mg per 100 g body weight. Catalase activity decreased to about 35% of that of the control at 42-48 h after the injection and recovered to the normal level at 96 h. Other peroxisomal enzymes, D-amino acid oxidase and urate oxidase, showed similar patterns of the activities to those of catalase. During the first 48 h after the injection of Triton WR-1339, the rate of catalase synthesis (ks) fell to below a detectable value, while that of the degradation (kd) did not show any significant change. On the other hand, during the period 48-96 h after the injection, the rate of the synthesis (ks) returned to the normal level though that of the degradation (kd) decreased to about 50% of the control.

Amitrole↗
PubMed1978

Some characteristics of peroxisomes in the slime mold, Dictyostelium discoideum.

Some characteristics of peroxisomes in the slime mold, Dictyostelium discoideum were studied biochemically. The slime mold contained only two peroxisomal enzymes, urate oxidase and catalase. Both activities were concentrated highest in the light mitochondrial fraction, while the highest activity of acid phosphatase as a marker of lysosomes was found in the heavy mitochondrial fraction. Sucrose density gradient centrifugation showed that the density of peroxisomes was 1.21--1.22 g/ml, and that of lysosomes was approximately 1.21 g/ml. When the light mitochondrial fraction was treated with deoxycholate, major activities of urate oxidase, catalase, and acid phosphatase were solubilized. With development of the slime mold, both activities of urate oxidase and catalse increased at the stationary stage (4--6 h after) to a great extent and also slightly at the aggregation stage (10--12 h), thereafter they decreased gradually. Acid phosphatase remained with moderately high activity till the culmination stage (18--20 h), and then disappeared rapidly. It was found that enhanced activities of peroxisomal enzymes at the stationary stage represented an increase in the particle fraction and supernatant. On the other hand, activities of acid phosphatase at the same stage increased two-fold only in the supernatant, while the activity in the particle fraction was reduced to one-half.

Acid Phosphatase↗