Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.1.18 (branching enzyme)
 628 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the diagnosis of metabolic myopathies the use of biochemical methods, in addition to morphological examination of muscle biopsies, is often necessary in order to identify a specific metabolic defect. In order to narrow down the spectrum of biochemical methods, extensive clinical investigation and morphological examination, including histology, enzyme histochemistry and electromicroscopy if necessary have to be done beforehand. Patients are classified in the following groups: 1) progressive muscular weakness and/or muscle wasting with storage of a) glycogen, b) lipid or c) mitochondrial alterations; 2) recurrent rhabdomyolysis induced by fasting or exercise a) with glycogen storage or b) without any specific morphological alterations. The spectrum of metabolic defects comprises disorders of glycogen and glucose metabolism (deficiency of acid maltase, debranching and branching enzyme, phosphorylase, phosphofructokinase and other glycolytic enzymes), lipid metabolism (carnitine deficiency, carnitine palmitoyl transferase deficiency), mitochondria (respiratory chain disorders, pyruvate dehydrogenase deficiency) and others such as adenylate deaminase deficiency. In some of these e.g. infantile acid maltase deficiency and mitochondriopathies, it is clinically more important when organs other than muscle are affected; however, muscle biopsy is a useful substrate for diagnosis of these metabolic disorders.
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PMID:[Diagnostic significance of muscle biopsies in metabolic myopathies. II. Clinical biochemistry]. 659 Sep 24

The investigations have been carried out on 116 guinea pigs divided in three groups: the control (first group), the experimental group with animals after acute anaphylactic shock (second group), the animals after histaminic shock (third group). The animals of the experimental (second) group were sensitized with 25% egg white suspension in 0.9% NaCl applied subcutaneously. The same animals were exposed to the action of the antigen in aerosol (second group). The healthy animals were exposed to the action of 1% solution of dihydrochloride histamine (third group). In acute anaphylactic shock a decrease of histoenzymatic activity of phosphorylase A and branching enzyme in liver parenchyma was observed. It has been concluded that in anaphylactic shock there occurred disturbances in the function of the phosphorylase A--branching enzyme system. In histaminic shock the phosphorylase reaction becomes intensified in numerous liver cells. This is possible because the exogenic histamine may lead to the activation of the enzymatic system under studies.
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PMID:Histochemical investigations on phosphorylase, branching enzyme and glycogen in guinea pig livers in experimental anaphylactic and histaminic shock. 666 10

The conversion of testosterone to 5 alpha-dihydrotestosterone, catalysed by 4-ene-steroid 5 alpha-reductase (3-oxo-5 alpha-steroid: NADP+ 4-ene-oxidoreductase EC 1.3.1.22) requires NADPH. In the present study, the role of flavins and Co-enzyme Q in this proton transfer was investigated for the first time in any male androgen target tissue. Flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) inhibited epididymal nuclear 4-ene-steroid 5 alpha-reductase activity non-competitively with respect to the substrate testosterone. However, neither the oxidized nor reduced forms of Co-enzyme Q affected the Kmapp or the Vmaxapp and the reduced form was unable to support catalytic activity in the absence of NADPH. Further investigation of the effects of flavins revealed that the inhibition was caused by an elevation of NADP+ in the incubations and that the incorporation of a NADPH generating system abolished the inhibition. Therefore, neither flavins nor Co-enzyme Q directly affected the 4-ene-steroid 5 alpha-reductase activity. Further evidence to support this conclusion was obtained when several inhibitors of electron transfer reactions failed to inhibit 4-ene-steroid 5 alpha-reductases from rat epididymides, prostate and seminal vesicles. These findings show that, in male rat androgen target tissues, the conversion of testosterone to 5 alpha-dihydrotestosterone does not require intermediates of electron transfer reactions. We propose that the reduction proceeds by the direct transfer of protons from NADPH to testosterone.
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PMID:Mechanism of 4-ene-steroid 5 alpha-reductase proton transfer in androgen target tissues. 674 43

The largest macromolecules of glycogen synthesized histochemically in tissue cells were spherical branching bodies composed of several large branches with many smaller branches, presumably containing a Meyer structure of alpha-1,4-1,6-glucosidic linkages. The synthesized macromolecules of glycogen were variable in size and structure, and were closely related to the activities of enzymes, phosphorylase, branching glycosyltransferase, and glycogen synthetase. The glycogen molecules appeared to be individually free in the cytoplasmic matrices. It is possible that they are synthesized there, and not related to the membrane system.
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PMID:Cellular synthesis of macromolecular glycogen and its deposition. 682 70

The reaction kinetics of single-stranded RNA replication were investigated by means of analytical and computer simulation methods. A model reaction mechanism is proposed that is in accord with the extensive experimental data available for the replication of various templates by the enzyme Q beta replicase. Despite the complexity of this mechanism, conventional concepts of steady-state and dynamic enzyme catalysis and plausible values of the rate and stability constants for the elementary reactions suffice to provide detailed understanding of RNA replication kinetics. The main features can be described with simple formulas that are analogous to traditional descriptions of enzyme kinetics.
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PMID:Kinetics of RNA replication. 686 Jun 47

In type IV glycogen storage disease, the abnormal storage material is a partially amylase-resistant, PAS-positive polysaccharide and a deficiency of the branching enzyme is present in virtually all cases studied so far. Electron microscopic, biochemical and enzymatic studies were carried out in a child presenting with the clinical and histological features of this disease. Electron microscopic study showed the amylase-resistant material to be fibrillar and poorly soluble in buffers. Iodine spectrum analysis indicated that the lambda max of the liver polysaccharide was between that of normal glycogen and that of typical type IV glycogen. Branching enzyme activity was not detectable in the patient's leucocytes but was close to normal in the liver and clearly detectable in cultured fibroblasts. These results suggest that the absolute value of the deficiency of the branching enzyme in the liver of patients with type IV glycogen storage disease could be questioned. Alternatively this patient as well as another one reported in the literature could be considered as subtypes of the disease in whom liver and fibroblast branching enzyme activity remains detectable in vitro.
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PMID:[A study of the abnormal polysaccharide in a child with type IV glycogen storage disease (author's transl)]. 694 1

The replication of a RNA template catalyzed by Q beta replicase was obtained in oleic acid/oleate vesicles simultaneously with the self-reproduction of the vesicles themselves. This was accomplished by entrapping the enzyme Q beta replicase, the RNA template, and the ribonucleotides ATP, CTP, GTP, and UTP inside the vesicles. The water-insoluble oleic anhydride was then added externally. It binds to the vesicle bilayer where it is catalytically hydrolyzed yielding the carboxylate surfactant in situ, which then brings about growth and reproduction of the vesicles themselves. This experiment is presented as a first approach to a synthetic minimal cell, in which the reproduction of the membrane and the replication of the internalized RNA molecules proceed simultaneously.
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PMID:Enzymatic RNA replication in self-reproducing vesicles: an approach to a minimal cell. 753 71

The branching enzyme N-acetylglucosaminyltransferase-V (GlcNAcT-V) recognizes the trisaccharide beta-D-GlcpNAc-(1-->2)-alpha-D-Man p-(1-->6)-beta-D-Glcp-O(CH2)7CH3 (1) as its minimum substrate. We report here the chemical synthesis of beta-D-GlcpNAc-(1-->2)-5a- carba-alpha-D-Manp-(1-->6)-beta-D-Glcp-O(CH2)7CH3 (2), a carbocyclic analog of 1 where the ring oxygen of the alpha-D-Manp residue is replaced by a methylene group. Trisaccharide 2 was found to be fully active as an acceptor for GlcNAcT-V, both with the enzyme isolated from hamster kidney and the one cloned from rat kidney. The kinetic parameters Km and Vmax for 1 and 2 were functionally equivalent. A preparative glycosylation reaction was performed using 2 as the acceptor with the cloned rat kidney enzyme. A tetrasaccharide formed by the addition of a Glc pNAc residue was the sole product as detected by 1H NMR spectroscopy and FAB mass spectrometry and was assigned the structure beta-D-GlcpNAc-(1-->2)-[beta-D-GlcpNAc-(1-->6)]-5a- carba-alpha-D-Manp-(1-->6)-beta-D-Glc p-O(CH2)7CH3 (13).
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PMID:Synthesis of beta-D-GlcpNAc-(1-->2)-5a-carba-alpha-D-Man p-(1-->6)-beta-D- Glcp-O(CH2)7CH3: a reactive acceptor analog for N-acetylglucosaminyltransferase-V. 766

Polyglucosan body diseases in adults, contrary to infantile cases (Andersen's disease or type IV glycogenosis or amylopectinosis), are usually not associated with a significant deficiency of the branching enzyme (= amylo-1,4-1,6 transglucosidase). We, therefore, report on a 19-year-old male with complete branching enzyme deficiency presenting with severe myopathy, dilative cardiomyopathy, heart failure, dysmorphic features, and subclinical neuropathy. His 14-year-old brother had similar symptoms and was erroneously classified by a previous muscle biopsy as having central core disease but could later be identified as also having polyglucosan body myopathy. The skeletal muscle, endomyocardiac, and sural nerve biopsies as well as the autopsy revealed extraordinarily severe deposits of polyglucosan bodies not only in striated and smooth muscle fibers, but also in histiocytes, fibroblasts, perineurial cells, axons and astrocytes. Occasional paracrystalline mitochondrial inclusions were also noted. Thus, this patient represents to our knowledge the first juvenile, familial case of polyglucosan body disease with total branching enzyme deficiency and extensive polyglucosan body storage.
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PMID:Juvenile hereditary polyglucosan body disease with complete branching enzyme deficiency (type IV glycogenosis). 768 69

In order to study infections due to Chlamydia trachomatis, we have compared semiquantitative PCR and Q beta replicase-amplified assays for detection of this organism. The PCR assay was directed against the C. trachomatis 16S rRNA gene. Quantitation was accomplished by adding known amounts of a plasmid containing a truncated segment of the 16S rRNA gene target to chlamydia-containing samples and then amplifying with a common primer set. The Q beta replicase assay consisted of reversible target capture of C. trachomatis 16S rRNA, which was followed by amplification of an RNA detector probe in the presence of the enzyme Q beta replicase. In a clinical matrix, the lower limit of detection of both the PCR and Q beta replicase assays was five elementary bodies. The Q beta replicase and PCR assays were quantitative over 10,000- and 1,000-fold ranges of organisms, respectively. Analysis of the effects of endocervical matrix on amplification was accomplished by examining 94 endocervical specimens by each technique. Both assays detected five of six culture-confirmed specimens as well as three culture-negative specimens. PCR inhibitors were detected in 13 specimens. The Q beta replicase assay, in contrast, showed no evidence of sample inhibition. The Q beta replicase and PCR assays should allow quantitative investigation of infections due to C. trachomatis. In addition, because it targets highly labile RNA, the Q beta replicase assay may facilitate investigations into the role of active persisting infection in culture-negative inflammatory conditions.
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PMID:Comparison of characteristics of Q beta replicase-amplified assay with competitive PCR assay for Chlamydia trachomatis. 769 67


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