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At least 19 recordsLinked to original sources
PubMed1976

Lack of glucose effect on the induction of 5-aminolevulinate synthetase and tyrosine aminotransferase in the isolated perfused rat liver.

In the isolated perfused rat liver, both 5-aminolevulinate synthetase and tyrosine aminotransferase were induced by the addition of 3.5 mmol/l allylisopropylacetamide and 58 mumol/l dexamethasone to the perfusion medium. Glucose (40 mmol/l) did not affect either the induction of these enzymes or the intrahepatic level of cyclic AMP. The results suggest that the glucose effect on the induction of 5-aminolevulinate synthetase and tyrosine aminotransferase in vivo is mediated by extrahepatic factors.

5-Aminolevulinate Synthetase↗
PubMed1975

Properties of 5-aminolaevulinate synthetase and its relationship to microsomal mixed-function oxidation in the southern armyworm (Spodoptera eridania).

1. Activity of 5-aminolaevulinate synthetase was measured in the midgut and other tissues of the last larval instar of the southern armyworm (Spodoptera eridania Cramer, formerly Prodenia eridania Cramer). 2. Optimum conditions for measuring the activity were established with respect to all variables involved and considerable differences from those reported for mammalian enzyme preparations were found. 3. Maximum activity (20 nmol/h per mg of protein) occurs 18-24 h after the fifth moult and thereafter decreases to trace amounts as the larvae age and approach pupation. 4. Synthetase activity was rapidly induced by oral administration (in the diet) of pentamethylbenzene, phenobarbital, diethyl 1,4-dihydro-2,4,6-trimethylpyridine-3, 5-dicarboxylate, and 2-allyl-2-isopropylacetamide. 5. Puromycin inhibited the induction of synthetase by pentamethylbenzene. 6. Induction of 5-aminolaevulinate synthetase correlated well with the induction of microsomal N-demethylation of p-chloro-N-methylaniline, except for phenobarbital, which induced the microsomal oxidase relatively more than the synthetase.

5-Aminolevulinate Synthetase↗
PubMed1976

Comparative studies of the effects of cyclic AMP, various hormones and chloramphenicol on the induction of delta-aminolevulinic acid synthetase and tyrosine aminotransferase in the organ-cultured chick embryo liver.

Induction of delta-aminolevulinic acid synthetase by allylisopropylacetamide in organ-cultured chick embryo liver was not appreciably influenced by any of cycli AMP, dibutyryl cyclic AMP, theophylline, glucose, insulin, glucagon, epinephrine, isoproterenol, and hydrocortisone, whereas the activity of tyrosine aminotransferase significantly increased in response to cyclic AMP and some of those hormones. Accumulation of delta-aminolevulinic acid synthetase in the cultured liver cytosol fraction was not appreciably increased by the addition of dibutyryl cyclic AMP or insulin to the incubation medium. Apparently the behaviors of the induction of delta-aminolevulinic acid synthetase in chick embryo liver in ovo and in vitro differ from those in the livers of adult chicken and rat. High concentrations of chloramphenicol suppressed significantly the allylisopropylacetamide-induced increase of delta-aminolevulinic acid synthetase as well as incorporation of 14C-leucine into proteins. The activity of tyrosine aminotransferase, however, was rather increased when relatively low concentrations of chloramphenicol were added to the medium.

5-Aminolevulinate Synthetase↗
PubMed1976

Erythroid differentiation in cultured Friend leukemia cells treated with metabolic inhibitors.

The induction of erythroid differentiation in the T3-C12 clone of Friend leukemia cells by dimethyl sulfoxide is accompanied by reduction in viral RNA-dependent DNA polymerase activity with increased cellular delta-aminolevulinic acid synthetase activity and hemoglobin synthesis. These cells were treated with a variety of compounds to determine whether other durgs are capable on inducing erythroid differentiation. While several hormones, inhibitors of RNA synthesis, organic solvents, inhibitors of DNA polymerase, sulfhydryl inhibitors, and inducers of delta-aminolevulinic acid synthetase administered singly did not stimulate hemoglobin synthesis like dimethyl sulfoxide, inhibitors of DNA and RNA synthesis such as adriamycin, mitomycin C, and hydroxyurea:mithramycin were synergistic in stimulating erythroid differentiation.

5-Aminolevulinate Synthetase↗
PubMed1976

Control of 5-aminolaevulinate synthetase activity in Rhodopseudomonas spheroides.

Rhodopseudomonas spheroides can grow in a defined medium with either light or oxygen as an energy source. Cells grown anaerobically or at very low oxygen tensions are rich in the photosynthetic pigment bacteriochlorophyll, whereas this pigment is virtually absent in cells grown under high oxygen tensions. Aminolaevulinate synthetase, the first enzyme on the pathway to bacteriochlorophyll, appears to play an important role in the control of bacteriochlorophyll synthesis. Thus, the enzyme has a high activity in extracts of pigmented cells and a low activity in extracts of non-pigmented cells. Further, oxygenation of a pigmented culture causes immediate cessation of pigment synthesis and produces a rapid fall in the activity of aminolaevulinate synthetase. This loss of activity appears to be due to the loss of an endogenous activator of the enzyme. Thus, pigmented cells contain cystine trisulphide, which at muM concentrations is an activator of aminolaevulinate synthetase, while oxygenation causes a rapid fall in the cellular content of this trisulphide. Cystathionase (EC 4.2.1.15) extracted from pigmented cells can catalyse the formation of cystine trisulphide from cystine, while rhodanese (EC 2.8.1.1) extracted from the same cells can catalyse the degradation of cystine trisulphide in the presence of sulphite to form cystine and thiosulphate. It is proposed that the cellular content of cystine trisulphide is controlled by changes in the levels of substrates for cystathionase and possibly rhodanese rather than changes in the amounts of these enzymes. Cystine trisulphide controls the activity of aminolaevulinate synthetase by converting a low-activity form of the enzyme (b-form) into a high-activity form (a-form). The fall in aminolaevulinate synthetase activity on oxygenation appears to be the result of cessation of conversion of b-form into a-form, along with a conversion of a-form into b-form. Factors affecting the equilibrium between the forms and the possible mechanisms for their interconversion are discussed.

5-Aminolevulinate Synthetase↗
PubMed1976

The effect of allyl compounds on hepatic microsomal mixed function oxidation and porphyrogenesis.

The activities of 5-aminolaevulinate (5-ALA) synthetase and of various microsomat drug-metabolising enzymes have been determined in the livers of rats pretreated with different drugs and chemicals containing the allyl group. Safrole, isosafrole and secobarbital gave rise to slight increases in 5-ALA synthetase, whereas alclophenac and triallyl cyanurate almost doubled the enzyme activity and the known porphyrogenic agents, allylisopropylacetamide (AIA) and allobarbital caused increases of 1.5- and 2.5-fold, respectively. Allobarbital induced the microsomal drug-metabolising enzymes while secobarbital had only a weak effect and alclophenac and triallyl cyanurate had no effect at all. From these results it is suggested that induction of the synthesis of cytochrome P-450 is not rate dependent on the synthesis haem and induction of porphyrin biosynthesis.

5-Aminolevulinate Synthetase↗
PubMed1979

Tests available for assessing recent exposure to inorganic lead compounds and their use for screening purposes.

This paper indicates the tests available for measurement of inorganic lead uptake by the body. The tests are listed and then considered individually. In the light of recent great interest in lead as a health hazard, the best methods for screening are considered: this includes biological and biochemical tests. It is emphasized that the U.K. favours blood lead estimation, the EEC countries other than Britain use blood lead but are considering more widespread use of delta-amino laevulinic acid dehydratase estimation in blood. Some authorities in the United States of America, on the other hand, favour a free erythrocyte protoporphyrin test. The advantages and disadvantages are brought out and some tests are mentioned only in order to exclude them as unsuitable. Suitability of tests for industrial checks and general screening of the population are differentiated. The conclusion is that blood lead still provides the best overall check of lead uptake.

5-Aminolevulinate Synthetase↗
PubMed1976

The effect of beta-adrenergic blocking agents on experimental porphyria induced by 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) in vivo and in vitro.

The effect of DL-propranolol on 3',5'-diethoxycarbonyl-1,4-dihydrocollidine-induced experimental porphyria was studied. DL-Propranolol, a beta-adrenergic blocking agent with non-specific membrane effects, partially inhibited 3',5'-diethoxycarbonyl-1,4-dihydrocollidine-induced delta-aminolevulinate synthetase activity both in rats and in chick embryo liver cells in culture. In rats, DL-propranolol decreased urinary delta-aminolevulinate and porphobilinogen but no change occurred in the 24-h urinary excretion of total porphyrins and in the concentration of porphyrins in the liver. In cultured chick embryo liver cells treated with 3',5'-diethoxycarbonyl-1,4-dihydrocollidine, DL-propranolol decreased accumulation of porphyrins in the medium. D-Propranolol, oxprenolol and quinidine acted like DL-propranolol in chick embryo liver cells in culture treated with 3',5'-diethoxycarbonyl-1,4-dihydrocollidine. Pindolol, practolol and lidocaine had no effect. Phenobarbitone had a synergistic effect on the induction of delta-aminolevulinate synthetase by 3',5'-diethoxycarbonyl-1,4-dihydrocollidine in cultures of chick embryo liver cells. This induction was partially inhibited by propranolol. However, the increased accumulation of porphyrins in the medium caused by 3',5'-diethoxycarbonyl-1,4-dihydrocollidine was inhibited by the addition of phenobarbitone. This inhibited induction was further decreased by propranolol. Most of our results indicate that the drugs tested act mainly by their effects on membranes.

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PubMed1977

Enzyme abnormalities in the porphyrias.

Evidence is presented that each of the porphyrias represents a different inborn error of metabolism in haem biosynthesis. Control of the pathway takes place by feedback repression and inhibition by haem of delta-aminolaevulinic-acid synthase. It is suggested that insituations where the activity of this enzyme is derepressed, prophobilinogen deaminase represents a secondary control step.

5-Aminolevulinate Synthetase↗
PubMed1979

Haematin therapy and leucocyte delta-aminolevulinic-acid-synthase activity in prolonged attack of acute porphyria.

The activity of leucocyte delta-aminolaevulinic-acid (A.L.A.) synthase was monitored throughout a prolonged attack of acute intermittent porphyria in a 29-year-old women. Clinical severity was associated with a pronounced increase in activity of this enzyme and high urinary excretion of A.L.A. Haematin therapy resulted in clinical improvement associated with a reduction in the activity of A.L.A. synthase and reduction in urinary excretion of A.L.A.

5-Aminolevulinate Synthetase↗
PubMed1976

Mechanism and stereochemistry of enzymic reactions involved in porphyrin biosynthesis.

5-Aminolaevulinate synthetase cataylses the condensation of glycine and succinyl-CoA to give 5-aminolaevulinic acid. At least two broad pathways may be considered for the initial C--C bond forming step in the reaction. In pathway A the Schiff base of glycine and enzyme bound pyridoxal phosphate (a) undergoes decarboxylation to give the carbanion (b) which then condenses with succinyl-CoA with the retention of both the original C2 hydrogen atoms of glycine. In pathway B, loss of a C2 hydrogen atom gives another type of carbanion (c) that reacts with succinyl-CoA. Evidence has been presented to show that the initial C--C bond forming event occurs via pathway B which involves the removal of the pro R hydrogen atom of glycine. Subsequent mechanistic and stereochemical events occurring at the carbon atom destined to become C5 of 5-aminolaevulinate have also been delineated.(Carticle) Several mechanistic alternatices for the formation of the two vinyl groups of haem from the propionate residues of the precursor, coproporphyrinogen III, have been examined. (see article). It is shown that during the biosynthesis both the hydrogen atoms resident at the alpha positions of the propionate side chains remain undisturbed thus eliminating mechanisms which predict the involvement of acrylic acid intermediates. Biosynthetic experiments performed with precursors containing stereospecific labels have shown that the two vinyl groups of haem are formed through the loss of pro S hydrogen atoms from the beta-positions of the propionate side chains. In the light of these results, three related mechanisms for the conversion, propionate leads to vinyl, have been considered. In order to study the mechanism of porphyrinogen carboxy-lyase reaction, stereo-specifically deuterated, tritiated-succinate was incorporated into the acetate residues of uroporphyrinogen III which on decarboxylation generated asymmetric methyl groups in coproporphyrinogen III and then in haem. Degradation of the latter yielded chiral acetate deriving from C and D rings of haem. Configurational analysis of this derivate acetate shows that the carboxy-lyase reaction proceeds with a retention of configuration.

5-Aminolevulinate Synthetase↗
PubMed1978

[Diagnosis of acute intermittent porphyria. Results of neurological, biochemical and genetic studies].

Neurological and biochemical studies have been performed on four AIP families with 21 members. Five patients suffered from manifested AIP (Uroporphyrinogen Synthase defect and characteristic urine findings); among their relatives five persons with latent AIP were detected and eight carriers of the genetic-enzymic defect (Uroporphyrinogen Synthase defect). Internal and neurological symptoms could be interpreted as a panneuropathy. Acute and chronical polyneuropathies could be observed as well as myelopathies and cerebral co-reactions. A frequent symptom dominating the crisis and the latent state of AIP were etiologically abscure 'myalgias.' The character of the course of AIP is various and dubious: beyond the 'classical' courses with its intermittent porphyric crises we observed one case which was characterized by a permanent crisis and a second case marked by a chronical, slow progredient course without any porphyric attacks.

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