Distribution of the multiple molecular forms of glucose-6-phosphate dehydrogenase in different physiological states

1979 ◽  
Vol 57 (5) ◽  
pp. 396-401 ◽  
Author(s):  
Hsiao-Lin Chang ◽  
Darold Holten ◽  
Rom Karin
Keyword(s):  
Enzyme Activity ◽  
Mammary Gland ◽  
Rat Liver ◽  
Specific Activity ◽  
Molecular Forms ◽  
Polyacrylamide Gels ◽  
Multiple Molecular Forms ◽  
Pregnancy And Lactation ◽  
Enzyme Specific Activity ◽  
Glucose 6 Phosphate Dehydrogenase

The distribution of the multiple molecular forms of rat liver and mammary gland glucose-6-phosphate dehydrogenase was determined by electrophoresis on 5% polyacrylamide gels. In both of these organs, changes in the distribution of enzyme activity among the several forms was slight even when approximately 20- to 40-fold changes in enzyme specific activity were achieved by fasting-refeeding experiments (for liver) or during pregnancy and lactation (for mammary gland), it was concluded that the induction of glucose-6-phosphate dehydrogenase in these two organs occurs without any major redistribution among the multiple molecular forms of this enzyme.

scholarly journals Regulation of lipogenic capacity in lactating rats

1982 ◽  
Vol 208 (3) ◽  
pp. 611-618 ◽  
Author(s):  
M R Grigor ◽  
A Geursen ◽  
M J Sneyd ◽  
S M Warren
Keyword(s):  
Mammary Gland ◽  
Fatty Acid ◽  
Malic Enzyme ◽  
Fatty Acid Synthase ◽  
Specific Activity ◽  
Mammary Glands ◽  
Lipogenic Enzymes ◽  
Pregnancy And Lactation ◽  
Specific Activities

1. The rate of mammary-gland lipogenesis measured in vivo from 3H2O was suppressed after decreasing the milk demand by decreasing the number of pups from ten to two or three, as well as by giving diets containing lipid [Grigor & Warren (1980) Biochem. J. 188, 61-65]. 2. The specific activities of the lipogenic enzymes fatty acid synthase, glucose 6-phosphate dehydrogenase and ‘malic’ enzyme increased between 6- and 10-fold in the mammary gland and between 2- and 3-fold in the livers during the first 10 days of lactation. The increases in specific activity coupled with the doubling of liver mass which occurred during pregnancy and lactation resulted in considerable differences in total liver activities when compared with virgin animals. 3. Although consumption of a diet containing 20% peanut oil suppressed the activities of the three lipogenic enzymes in the livers, only the ‘malic’ enzyme was affected in the mammary glands. 4. In contrast, decreased milk demand did not affect the specific activities of any of the liver enzymes, whereas it resulted in suppression of all three lipogenic enzymes of the mammary glands. There was no effect on either the cytoplasmic malate dehydrogenase or the lactate dehydrogenase of the mammary gland. 5. In all the experiments performed, the activity of the fatty acid synthase correlated with the amount of material precipitated by the rabbit antibody raised against rat fatty acid synthase.

scholarly journals Reconstitution of purified Wistar rat liver bilirubin UDP-glucuronyltransferase into Gunn-rat liver microsomes

1982 ◽  
Vol 201 (3) ◽  
pp. 653-656 ◽  
Author(s):  
B Burchell
Keyword(s):  
Enzyme Activity ◽  
Rat Liver ◽  
Specific Activity ◽  
Liver Microsomes ◽  
Wistar Rat ◽  
Transferase Activity ◽  
Rat Liver Microsomes ◽  
Phosphatidylcholine Liposomes ◽  
Gunn Rat ◽  
Rigid Environment

1. Reconstitution of purified bilirubin UDP-glucuronyltransferase from Wistar-rat liver into Gunn-rat liver microsomes provides a better environment than phosphatidylcholine liposomes, such that the final specific activity of the Wistar-rat liver enzyme was increased up to 85 units/mg of protein. 2. Gunn- and Wistar-rat liver microsomes were equally effective for reconstitution of the purified enzyme. 3. The transferase activity does not appear to be fully expressed in the more rigid environment of foetal Wistar-rat liver microsomes. 4. These reconstitution experiments reveal a final specific activity for the purified bilirubin UDP-glucuronyltransferase consistent with the capacity of the whole rat liver to glucuronidate bilirubin and indicate that the absence of this enzyme activity in Gunn-rat liver microsomes is not due to an abnormal microenvironment.

A new bilirubin-degrading enzyme from orange peels

1988 ◽  
Vol 66 (11) ◽  
pp. 1248-1252 ◽  
Author(s):  
Tai-Wing Wu ◽  
Grace S. Li
Keyword(s):  
Enzyme Activity ◽  
Absorption Spectrum ◽  
Cholic Acid ◽  
Rat Liver ◽  
Specific Activity ◽  
Unconjugated Bilirubin ◽  
Proteinase K ◽  
Bilirubin Oxidase ◽  
Orange Peels ◽  
Poorly Soluble

A novel enzyme activity that catalyzes the degradation of unconjugated bilirubin (Bu) has been demonstrated in extracts of the peels of edible oranges. Unlike the few known bilirubin-oxidizing enzymes, the orange enzyme does not produce biliverdin as a product, does not seem to require oxygen, and has a unique absorption spectrum of its products. Even at the crude stage, the enzyme has a specific activity that is 10 and 20 times higher, respectively, than those reported for the crude or partially purified Bu-degrading enzymes from mushrooms and rat liver. The enzyme has apH optimum near 7.5 and a Km value of 50–100 μM for Bu. The enzyme is remarkably stable, retaining over 50% activity after prolonged digestion with proteinase K or heating at 100 °C. Similar treatments inactivated the bilirubin oxidase from Myrothecium verrucaria MT-1. The enzyme is poorly soluble in water but can be partially solubilized with cholic acid, with a doubling in specific activity.

scholarly journals Inactivation of glucose 6-phosphate dehydrogenase during germination and outgrowth of Bacillus cereus T endospores

1975 ◽  
Vol 148 (2) ◽  
pp. 259-268 ◽  
Author(s):  
M Orlowski ◽  
M Goldman
Keyword(s):  
Enzyme Activity ◽  
Specific Activity ◽  
Proteolytic Enzymes ◽  
Polyacrylamide Gel Electrophoresis ◽  
Total Activity ◽  
Cellular Protein ◽  
Metabolic Energy ◽  
Supernatant Fraction ◽  
Stage Of Development ◽  
Glucose 6 Phosphate Dehydrogenase

The specific activity and total activity of glucose 6-phosphate dehydrogenase (EC 1.1.1.49) under conditions of complete cell breakage fall 10-20-fold during a 3h period of spore germination and outgrowth. The spores must germinate (lose refractility), but do not have to undergo outgrowth, for the loss of activity to occur. Glucose 6-phosphate dehydrogenase activity from cells as any stage of development is completely stable in extracts at 4 degrees C or 30 degrees C. All of the enzyme activity is found in a soluble (50000g supernatant) fraction and remains completely soluble throughout development. Soluble protein and total cellular protein remain constant for about 2h. Proteinases could not be detected or protein turnover demonstrated during the morphogenetic process. Phenylmethanesuophony fluoride and o-phenanthroline, inhibitors of proteolytic enzymes, do not prevent glucose 6-phosphate dehydrogenase inactivation when added to whole cells. Mixing experiments show no inhibitor of glucose 6-phosphate dehydrogenase to be present in late-stage cells. The enzyme is not excreted into the culture medium. Chloramphenicol and rifampicine immediately stop protein synthesis and development but not the inactivation of glucose 6-phosphate dehydrogenase. NaN3, 2,4-dinitrophenol or anaerobiosis immediately stop development and prevent the loss of enzyme activity. A requirement for metabolic energy is therefore probable. Extracts of spores pre-labelled with L[14C]leucine were made at various stages of morphogenesis and subjected to polyacrylamide-gel electrophoresis. Glucose 6-phosphate dehydrogenase, which was identified by a specific stain, did not lose 14C label, and therefore may not be degraded during the inactivation process.

scholarly journals Intracellular enzymes of collagen biosynthesis in rat liver as a function of age and in hepatic injury induced by dimethylnitrosamine. Purification of rat prolyl hydroxylase and comparison of changes in prolyl hydroxylase activity with changes in immunoreactive prolyl hydroxylase

1976 ◽  
Vol 158 (2) ◽  
pp. 369-376 ◽  
Author(s):  
J Risteli ◽  
L Tuderman ◽  
K I Kivirikko
Keyword(s):  
Enzyme Activity ◽  
Rat Liver ◽  
Hepatic Injury ◽  
Specific Activity ◽  
Prolyl Hydroxylase ◽  
Newborn Rats ◽  
Hydroxylase Activity ◽  
Immunoreactive Protein ◽  
Molecular Weights ◽  
Polypeptide Chains

Prolyl hydroxylase was purified from newborn rats by affinity chromatography using poly(L-proline), and antiserum to the enzyme was prepared in rabbits. The rat prolyl hydroxylase was similar to the chick and human enzymes with respect to specific activity, molecular weight and molecular weights of the polypeptide chains. The activity of prolyl hydroxylase and the content of immunoreactive enzyme were measured in rat liver as a function of age in experimental hepatic injury. Active prolyl hydroxylase comprised about 13.2% of the total immunoreactive protein in the liver of newborn rats and the value decreased to about 3.6% at the age of 420 days. This decrease was due to a decrease in the enzyme activity, whereas only minor changes were found in the content of the immunoreactive protein. In hepatic injury, a significant increase was found in the ratio of active enzyme to total immunoreactive protein, owing to an increase in the enzyme activity. The data indicate that prolyl hydroxylase activity in rat liver is controlled in part by a mechanism which does not involve changes in the content of the total immunoreactive protein.

scholarly journals The effect of phenobarbital on the submicrosomal distribution of uridine diphosphate glucuronyltransferase from rat liver

1970 ◽  
Vol 117 (2) ◽  
pp. 319-324 ◽  
Author(s):  
G. J. Mulder
Keyword(s):  
Enzyme Activity ◽  
Density Gradient ◽  
Rat Liver ◽  
Microsomal Fraction ◽  
Specific Activity ◽  
Sucrose Density Gradient ◽  
Male Rats ◽  
Uridine Diphosphate ◽  
Triton X

1. The detergent Triton X-100 activates UDP glucuronyltransferase from rat liver in vitro six- to seven-fold with p-nitrophenol as substrate. The enzyme activity when measured in the presence of Triton X-100 is increased significantly by pretreatment of male rats with phenobarbital for 4 days (90mg/kg each day intraperitoneally). If no Triton X-100 is applied in vitro such an increase could not be shown. In all further experiments the enzyme activity was measured after activation by Triton X-100. 2. The Km of the enzyme for the substrate p-nitrophenol does not change on phenobarbital pretreatment. 3. When the microsomal fraction from the liver of untreated rats is subfractionated on a sucrose density gradient, 47% of the enzyme activity is recovered in the rough-surfaced microsomal fraction, which also has a higher specific activity than the smooth-surfaced fraction. 4. Of the increase in activity after the phenobarbital pretreatment 50% occurs in the smooth-surfaced fraction, 19% in the rough-surfaced fraction and 31% in the fraction located between the smooth- and rough-surfaced microsomal fractions on the sucrose density gradient. 5. The latency of the enzyme in vitro, as shown by the effect of the detergent Triton X-100, is discussed in relation to the proposed heterogeneity of UDP glucuronyltransferase.

scholarly journals Immunochemical studies with soluble and mitochondrial pyruvate carboxylase activities from rat tissues

1970 ◽  
Vol 119 (4) ◽  
pp. 735-742 ◽  
Author(s):  
F. J. Ballard ◽  
R. W. Hanson ◽  
Lea Reshef
Keyword(s):  
Adipose Tissue ◽  
Mammary Gland ◽  
Brown Adipose Tissue ◽  
Rat Liver ◽  
White Adipose Tissue ◽  
Pyruvate Carboxylase ◽  
Specific Activity ◽  
Rat Liver Mitochondria ◽  
Rat Tissues ◽  
Brown Adipose

1. Pyruvate carboxylase (EC 6.4.1.1), purified from rat liver mitochondria to a specific activity of 14 units/mg, was used for the preparation of antibodies in rabbits. 2. Tissue distribution studies showed that pyruvate carboxylase was present in all rat tissues that were tested, with considerable activities both in gluconeogenic tissues such as liver and kidney and in tissues with high rates of lipogenesis such as white adipose tissue, brown adipose tissue, adrenal gland and lactating mammary gland. 3. Immunochemical titration experiments with the specific antibodies showed no differences between the inactivation of pyruvate carboxylase from mitochondrial or soluble fractions of liver, kidney, mammary gland, brown adipose tissue or white adipose tissue. 4. The antibodies were relatively less effective in reactions against pyruvate carboxylase from sheep liver than against the enzyme from rat tissues. 5. Pyruvate carboxylase antibodies did not inactivate either propionyl-CoA carboxylase or acetyl-CoA carboxylase from rat liver. 6. It is concluded that pyruvate carboxylase in lipogenic tissues is similar antigenically to the enzyme in gluconeogenic tissues and that the soluble activities of pyruvate carboxylase detected in many rat tissues do not represent discrete enzymes but are the result of mitochondrial damage during tissue homogenization.

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