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At least 649 records · Page 36Linked to original sources
PubMed1969

Bacteriochlorophyll and heme synthesis in Rhodopseudomonas spheroides: possible role of heme in regulation of the branched biosynthetic pathway.

Synthesis of heme, measured by incorporation of iron-59, and of bacteriochlorophyll was studied with wild-type and mutant strains of Rhodopseudomonas spheroides. The wild type formed heme from glycine and succinate at one-fortieth the rate of bacteriochlorophyll under anaerobic-light conditions. Added delta-aminolevulinate stimulated heme synthesis 10-fold without increasing bacteriochlorophyll production. Heme synthesis from glycine and succinate was increased when the magnesium branch of the biosynthetic path was curtailed by mutation or by p-fluorophenylalanine or 8-azaguanine. Synthesis of bacteriochlorophyll by the wild type from glycine and succinate stopped immediately after addition of puromycin, but heme production continued for a period. Porphyrins and other precursors did not appear upon addition of puromycin alone, but simultaneous addition of o-phenanthroline resulted in the accumulation of coproporphyrin. Production of this porphyrin by a mutant strain with impaired ability to form heme was unaffected by puromycin. Heme synthesis from glycine and succinate or from delta-aminolevulinate was decreased by limitation of methionine; it is suggested that coproporphyrin accumulation from glycine and succinate under conditions of methionine deficiency results from relief of feedback inhibition of delta-aminolevulinate synthase by heme. The development of delta-aminolevulinate synthase activity in response to low aeration is prevented by addition of delta-aminolevulinate. This repressive action of the latter is abolished when its conversion to heme is impeded by mutation or by methionine deficiency. It is suggested that heme, the quantitatively minor end product of the branched biosynthetic pathway, may regulate the flow of common intermediates when utilization of protoporphyrin by the magnesium branch is diminished. This regulation may be exerted by feedback inhibition of delta-aminolevulinate synthase and also by repression of enzyme formation.

Amino Acids↗
PubMed1978

The effects of water restriction and water loading on urinary excretion of lead, delta-aminolevulinic acid and coproporphyrin.

Alterations in daily urinary excretion of lead, delta-aminolevulinic acid (ALA), coproporphyrin, creatinine and total solutes following water restriction and water loading were examined in nine lead workers. Excretion of lead, ALA and total solutes was significantly decreased when urinary volume was reduced, showing that these values are dependent on urinary volume: conversely, excretion of coproporphyrin and creatinine was independent of urinary volume. Excretion of lead and total solutes was also dependent on creatinine excretion. The renal excretory mechanism of lead, ALA and coproporphyrin is discussed in the light of these findings.

Adult↗
PubMed1983

Failure of delta-aminolaevulinic acid and porphobilinogen to alter renal salt and water excretion in the dog.

We tested the hypothesis that the hyponatremia commonly observed in patients with acute hepatic porphyria is mediated by the presence of aminolaevulinic acid (ALA) and (or) porphobilinogen (PBG) at the level of the renal tubule to alter water handling, or at the level of the nervous system to release antidiuretic hormone (ADH). When these substances were infused intravenously into hydropenic dogs, there was no effect on systemic hemodynamics or renal function. Neither ALA or PBG, when infused directly into the renal circulation of water-loaded dogs, could effect a decrease in urinary flow, osmolar clearance, or renal perfusion. Similar results were obtained when these substances were infused directly into the renal circulation of hydropenic dogs. When ALA was administered directly into the carotid artery of nine water-loaded dogs and eight hydropenic dogs, there was again no effect on systemic hemodynamics or renal function. These data suggest that ALA (and PBG) have no effect on the renal excretion of sodium or water, and ALA does not cause the release of ADH. The hyponatremia of porphyria may be related to factors other than the elevated plasma levels of ALA and PBG.

Aminolevulinic Acid↗
PubMed1971

The measurement of the synthetic rate of bilirubin from hepatic hemes in patients with acute intermittent porphyria.

A new method for the direct measurement in vivo of the synthetic rate of bilirubin from hepatic hemes is proposed. This method depends on the application of the labeled precursor-product relationship to the hepatic pool of porphobilinogen, which is a common precursor of both urinary porphobilinogen and hepatic-synthesized bilirubin. The hepatic pool of porphobilinogen is labeled by means of an intravenous injection of delta-aminolevulinic acid-4-(14)C. The proportion of total bilirubin production which is derived from hepatic hemes is calculated from the ratio of the mean (14)C specific activities of stercobilin and porphobilinogen estimated in pooled specimens of feces and urine, respectively. The method can be most readily applied to patients with acute intermittent porphyria, as the appreciable quantities of prophobilinogen in the urine of these patients greatly facilitate the measurement of porphobilinogen-(14)C specific activity. In three patients with acute intermittent porphyria, values obtained for the synthetic rate of bilirubin from hepatic hemes were 20.7, 15.8, and 13.3% of total bilirubin production.

Acute Disease↗
PubMed1977

[A new method for the clinical determination of urinary porphobilinogen and delta-aminolevulinic acid].

A new method has been developed for clinical determination of porphobilinogen and delta-aminolevulinic acid in urine. Compared with the method of Mauzerall and Granick, being the most commonly used method for clinical application, there is an essential reduction of work and needed time. During the flow of 0.5 ml urine on a 0.7 cm x 2 cm column of macroporous cation exchange resin in H+-form porphobilinogen and delta-aminolevulinic acid are bound to the resin. After rinsing the column with 3 ml N acetic acid and 1 ml H2O the bound hemprecursors were eluted with 5 ml buffer. Concentration of porphobilinogen and of the pyrrol, synthesized from delta-aminolevulinic acid by Knorr-reaction is measured photometrically at 546 nm after Ehrich-reaction. After a short-time regeneration of columns -- 5 ml buffer, 3 ml N acetic acid -- these columns can be reused at least 20 times.

Aminolevulinic Acid↗
PubMed1987

[Porphobilinogen synthase activity and porphyrin biosynthesis in the erythrocytes after incubation with delta-aminolevulinic acid in pernicious anemia patients].

The activity of PBG-S was studied in erythrocytes according the standard method of Berlin and Schaller as well as the biosynthesis of porphyrins after incubation with delta-aminolevulinic acid according to Idel'son in a control group of 40 healthy males and females and 15 patients with pernicious anemia. The activity of porphobilinogen synthase and the level of porphobilinogen were elevated in the patients studied. The total quantity of synthesized porphyrins is increased as regards the control group of healthy on the account of the enhanced biosynthesis of uroporphyrins and coproporphyrins, whereas the quantity of the protoporphyrin synthesized was reduced. The changes established reflect the secondary disordered heme synthesis in the patients with pernicious anemia.

Aminolevulinic Acid↗