Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.5.1.4 (deaminase)
5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Numerous porphyrin auxotrophic mutants have been isolated from the 168 trpC2 strain of Bacillus subtilis by selection with streptomycin. Some of them could be supplemented with ALA while the majority grew only in the presence of haemin. Among the latter strains, the syntropism test allowed to distinguish two groups different in phenotype, viz., feeders accumulating ALA and non-feeders accumulating instead of ALA other porphyrin intermediates. On the basis of transductional studies, feeders and non-feeders could be divided into two and four groups, respectively. Biochemical investigation revealed that, with one exception, one enzyme of the porphyrin biosynthesis was coordinated to each hem locus. The following genes were identified:hemB yields ALA-dehydrase;hemC yields PBG-deaminase; hemE yields uroporphyrinogen decarboxylases; hemF yields coproporphyrinogen oxidase; hemG yields protoporphyrin-iron-chelatase.
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PMID:Genetic and biochemical analysis of haemin dependent mutants of Bacillus subtilis. 80 3

Porphobilinogen-deaminase from Saccharomyces cerevisiae has been isolated and partially purified 80- and 230-fold in the absence or presence of phenylmethylsulphonyl fluoride, respectively. Some properties of the isolated enzyme were studied. Porphyrin formation was linear with time and protein concentration. Optimum pH was about 7.5-7.8. Molecular mass of the protein was 30,000 +/- 3000 Dalton when the enzyme was purified in the presence of phenylmethylsulphonyl fluoride. A less active and unstable 20,000 Da molecular mass species was obtained when purification was performed in the absence of the protease inhibitor. Porphobilinogen-deaminase exhibited classical Michaelis-Menten kinetics. The apparent Km for uroporphyrinogen formation was 19 microM; Vmax was 3.6 nmol uroporphyrin/h and the Hill coefficient was n = 1. Also the action of several reagents on the activity was studied. Protective thiol agents had no effect. Heavy metals inhibited both porphyrin formation and porphobilinogen consumption, but known sulphydryl inactivating chemicals inhibit the former without modifying the latter. Ammonium ions had no effect on the activity while hydroxylamine completely inhibited both porphyrin formation and porphobilinogen consumption.
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PMID:Studies on porphobilinogen-deaminase from Saccharomyces cerevisiae. 181 12

Porphobilinogen-deaminase (PBG-D) and PBG-D-isomerase complex (PBG-D-I) from pig liver were isolated and partially purified. Uroporphyrinogen I and III formation was found to be linear with time and protein concentration. Optimal pH was about 7.4 and 7.6-7.8 for PBG-D and PBG-D-I complex, respectively. Some properties of the isolated enzymes were studied. Molecular mass determination gave a value of 40,000 Da for PBG-D and 50,000 Da for the complex. Both enzymes exhibited classical Michaelis-Menten kinetics. Km and Vmax parameters were estimated. The effect of several divalent cations, ammonia and thiol reagents was also investigated. The differential action of some of these chemicals on PBG-D and PBG-D-I system would suggest that PBG-D and isomerase may not be only physically adjacent but actually associated.
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PMID:Studies on uroporphyrinogen biosynthesis in pig liver. 181 18

The formation of the dipyrromethane cofactor of Escherichia coli porphobilinogen deaminase was shown to depend on the presence of 5-aminolevulinic acid. A hemA- mutant formed inactive deaminase when grown in the absence of 5-aminolevulinic acid since this strain was unable to biosynthesize the dipyrromethane cofactor. The mutant formed normal levels of deaminase, however, when grown in the presence of 5-aminolevulinic acid. Porphobilinogen, the substrate, interacts with the free alpha-position of the dipyrromethane cofactor to give stable enzyme-intermediate complexes. Experiments with regiospecifically labeled intermediate complexes have shown that, in the absence of further substrate molecules, the complexes are interconvertible by the exchange of the terminal pyrrole ring of each complex. The formation of enzyme-intermediate complexes is accompanied by the exposure of a cysteine residue, suggesting that substantial conformational changes occur on binding substrate. Specific labeling of the dipyrromethane cofactor by growth of the E. coli in the presence of 5-amino[5-14C]levulinic acid has confirmed that the cofactor is not subject to catalytic turnover. Experiments with the alpha-substituted substrate analogue alpha-bromoporphobilinogen have provided further evidence that the cofactor is responsible for the covalent binding of the substrate at the catalytic site. On the basis of these cumulative findings, it has been possible to construct a mechanistic scheme for the deaminase reaction involving a single catalytic site which is able to catalyze the addition or removal of either NH3 or H2O. The role of the cofactor both as a primer and as a means for regulating the number of substrates bound in each catalytic cycle is discussed.
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PMID:Investigation into the nature of substrate binding to the dipyrromethane cofactor of Escherichia coli porphobilinogen deaminase. 306 32

The procedures for the generation of enzyme-substrate complexes from labeled porphobilinogens [(2,11-13C]PBG and [2,6,11-3H]PBG) with deaminase and the methods employed for their purification are described. Use of 13C NMR failed to detect the substrate bound to the enzyme, suggesting that the line width must be inordinately large. The complex was found to disproportionate with time when stored at 25 degrees C. However, enzyme-bound uroporphyrinogen I (uro'gen I) was detected, both in the intact protein and in the oligopeptides from tryptic digestion and peptide mapping. The first detection of an enzyme-substrate complex by 3H NMR is described for [3H]PBG and deaminase. The line widths of the observed resonances were found to be extremely large and dependent upon temperature, giving chemical shifts that suggest the involvement of a sulfhydryl group as the nucleophilic enzyme group that binds the substrate. The catalytic competence of this complex was also demonstrated by displacing bound [3H]PBG with unlabeled PBG. During the resultant formation of [3H]uro'gen I, a transient low-intensity signal was detected that has been tentatively assigned to the highly reactive azafulvene species, proposed in several mechanistic schemes for porphyrin biosynthesis.
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PMID:Biosynthesis of porphyrins and corrins. 2. Isolation, purification, and NMR investigations of the porphobilinogen-deaminase covalent complex. 348 2

The activity of the following enzymes involved in the biosynthesis of porphyrins was determined in two strains of Trypanosoma cruzi (Y and CL) grown in two culture media (LIT and Warren): succinyl coenzyme A synthetase (Suc.CoA-S), 5-aminolevulinate synthetase (ALA-S), 4,5-dioxovaleric acid transaminase (DOVA-T), 5-aminolevulinate dehydratase (ALA-D), porphobilinogenase (PBGase), deaminase and heme synthetase (Heme-S). The amount of 5-aminolevulinic acid (ALA) and porphobilinogen, porphyrins and heme was also determined. ALA and PGB were detected in both strains of T. cruzi. However, ALA was not detected in epimastigotes of the Y strain grown in the LIT medium. The content of ALA and PBG varied according to the strain and the growth medium. No free porphyrins and heme were detected in both strains of T. cruzi. The activity of Suc.CoA-S and DOVA-T was markedly influenced by the strains of the parasite and the growth medium. No significant DOVA-T activity was detected in epimastigotes of the CL strain grown in the Warren's medium. No significant activity of ALA-D, PBGase and deaminase was detected in T. cruzi. Activity of Heme-S was detected in both strains of T. cruzi when mesoporphyrin, protoporphyrin or deuteroporphyrin was used as substrate. The enzyme activity was influenced by the strain of the parasite, the growth medium and the substrate used.
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PMID:Heme synthesis in Trypanosoma cruzi: influence of the strain and culture medium. 351 Aug 10

The activity of the following enzymes involved in the biosynthesis of porphyrins was determined in endosymbiote-free and endosymbiote-containing Crithidia deanei grown in a chemically defined medium: succinyl Coenzyme A synthetase (Suc.CoA-S), 5-aminolevulinate synthetase (ALA-S), 4,5-dioxovaleric acid transaminase (DOVA-T), 5-aminolevulinate dehydratase (ALA-D), porphobilinogenase (PBGase), deaminase and heme synthetase (Heme-S). The amount of 5-aminolevulinic acid (ALA) and porphobilinogen, porphyrins and heme was also determined. ALA and PBG were detected in C. deanei. The levels of free porphyrins was low. Heme concentration was nil. The activity of ALA-D, deaminase and PBGase was not detected in C. deanei. The activity of Suc.CoA-S and ALA-S were twice higher in symbiote-containing than in aposymbiotic C. deanei. Aposymbiotic cells had a higher activity of DOVA-T than symbiote-containing cells. The level of Heme-S, measured using protoporphyrin as substrate, was twice as high in symbiote-containing than in symbiote-free cells.
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PMID:Heme synthesis in Crithidia deanei: influence of the endosymbiote. 393 49

A simpler method for purifying human red cell deaminase, using a mixture of n-butanol and chloroform, which denatures hemoglobin, followed by ammonium sulphate fractionation, heat treatment, Sephadex G-100 and DEAE-cellulose chromatography, yielding a 3400 fold purified enzyme is described. Some properties of purified deaminase were studied. The enzyme seems to have a strict requirement for oxygen, neither PBG consumption nor uroporphyrinogens formation were measured under anaerobiosis. Uroporphyrinogens formation was linear with both protein and time over a wide range of enzyme concentration and up to 2 h. The optimum pH was 7.4 and the mol. wt was 40,000 +/- 4000. The enzyme was heat-stable and increased its activity by heating. Ammonium and hydroxylamine ions inhibited the reaction. K+ and Na+ ions did not greatly affect activity, while most divalent cations tested significantly diminished uroporphyrinogen formation and to a lesser degree PBG consumption. Direct plots of velocity against PBG concentration were hyperbolic, however double-reciprocal plots were non-linear, Hill plots gave an n value of 2 and Eadie plots were bell-shaped, indicating the existence of weakly positive cooperative effect between 2 binding sites for PBG per molecule of deaminase.
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PMID:Human red cell porphobilinogen deaminase. A simpler method of purification and some unusual properties. 400 48

Porphobilinogen (PBG) deaminase catalyzes the formation of the linear tetrapyrrole, hydroxymethylbilane, from four molecules of PBG. The tetrapyrrole is either converted to uroporphyrinogen III by uroporphyrinogen cosynthetase or nonenzymatically cyclized to uroporphyrinogen I. Methods for the biosynthesis of gram quantities of PBG and for the determination of PBG-deaminase specific activity in various tissues were developed. Using this assay, the PBG-deaminase activities in human erythrocytes, brain, liver and cultured fibroblasts and lymphoblasts as well as various rat tissues were determined as reference values. In addition, the conditions for the use of this assay in the enzymatic diagnosis of heterozygotes for acute intermittent porphyria were established.
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PMID:Porphobilinogen deaminase: methods and principles of the enzymatic assay. 714 Jul 17

Porphobilinogen is the substrate of two enzymes: porphobilinogen deaminase and porphobilinogen-oxygenase. The first one transforms it into the metabolic precursors of heme and the second diverts it from this metabolic pathway by oxidizing porphobilinogen to 5-oxopyrrolinones. Rat blood is devoid of porphobilinogen-oxygenase under normal conditions while it carries porphobilinogen-deaminase activity. When the rats were submitted to hypoxia (pO2 = 0.42 atm) for 18 days, the activity of porphobilinogen-oxygenase appeared at the tenth day of hypoxia and reached the maximum at the 14-16th day. It decreased to a half after 2 days (half-life of the enzyme) and disappeared after 4 days of return to normal oxygen pressure. Porphobilinogen-deaminase activity increased after the first day of hypoxia, reached a maximum at the 14-16th day and did not decrease to normal values until the 15th day after return to normal oxygen pressure. The activities of both porphobilinogen-oxygenase and porphobilinogen-deaminase were induced by administration of erythropoietin. When rats were made anaemic with phenylhydrazine, porphobilinogen-oxygenase activity also appeared in the blood cells. Although the reticulocyte concentration was higher when compared to that obtained under hypoxia, the activities of the oxygenase obtained under both conditions were comparable. Porphobilinogen-deaminase activity was always closely related to the reticulocyte content. The appearance of porphobilinogenase-oxygenase under the described erythropoietic conditions was due to a de novo induction of the enzyme, as shown by its inhibition with actinomycin D and cycloheximide. Porphobilinogen-oxygenase as well as porphobilinogen-deaminase were present in the rat bone marrow under normal conditions. Their activities increased in phenylhydrazine treated rats. The properties and kinetics of porphobilinogen-oxygenase from the rat blood and bone marrow were determined and found it differ in several aspects.
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PMID:Induction of porphobilinogen oxygenase and porphobilinogen deaminase in rat blood under conditions of erythropoietic stress. 726 Jan 10


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