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

A Butyrivibrio fibrisolvens H17c glgB gene, was isolated by direct selection for colonies that produced clearing on starch azure plates. The gene was expressed in Escherichia coli from its own promoter. The glgB gene consisted of an open reading frame of 1,920 bp encoding a protein of 639 amino acids (calculated Mr, 73,875) with 46 to 50% sequence homology with other branching enzymes. A limited region of 12 amino acids showed sequence similarity to amylases and glucanotransferases. The B. fibrisolvens branching enzyme was not able to hydrolyze starch but stimulated phosphorylase alpha-mediated incorporation of glucose into alpha-1,4-glucan polymer 13.4-fold. The branching enzyme was purified to homogeneity by a simple two-step procedure; N-terminal sequence and amino acid composition determinations confirmed the deduced translational start and amino acid sequence of the open reading frame. The enzymatic properties of the purified enzyme were investigated. The enzyme transferred chains of 5 to 10 (optimum, 7) glucose units, using amylose and amylopetin as substrates, to produce a highly branched polymer.
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PMID:Characterization of the Butyrivibrio fibrisolvens glgB gene, which encodes a glycogen-branching enzyme with starch-clearing activity. 193 80

Neurospora crassa branching enzyme [EC 2.4.1.18] acted on potato amylopectin or amylose to convert them to highly branched glycogen-type molecules which consisted of unit chains of six glucose units. The enzyme also acted on the amylopectin beta-limit dextrin, indicating that the enzyme acted on internal glucose chains as well as outer chains. By the combined action of N. crassa glycogen synthase [EC 2.4.1.11] and the branching enzyme, a glycogen-type molecule was formed from UDP-glucose. In the presence of primer glycogen, the glucose transfer reaction was accelerated by the addition of branching enzyme. On the other hand, the glucose transfer reaction by glycogen synthase did not occur without primers. When the branching enzyme was added, the glucose transfer occurred after a short time lag. This recovery of the glucose transfer reaction did not occur upon addition of the inactivated branching enzyme. The structure of the product formed by the combined action of the two enzymes was different from that of the intact N. crassa glycogen with respect to the distribution patterns of the unit chains.
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PMID:Mode of action of glycogen branching enzyme from Neurospora crassa. 213 54

The interaction of Neurospora crassa branching enzyme (1,4-alpha-D-glucan:1,4-alpha-D-glucan 6-alpha-(1,4-alpha-glucano)-transferase) [EC 2.4.1.18] with substrate glycogen or amylopectin was studied by affinity electrophoresis. By this method, the dissociation constants (K) of the branching enzyme for oyster glycogen (CL-12.2, OCL-6.3) and for potato amylopectin (CL-20, OCL-12.8) were determined to be 13.3 mM and 0.355 mM, respectively. The affinity of the enzyme to the substrate glycogen increased with the increase of outer chain length (OCL) of the substrate. The thermodynamic parameters of the branching reaction were obtained from the changes of K values of the enzyme-substrate complex at various temperatures. The value of heat change (delta H degree) of the branching reaction for amylopectin was -27.7 kcal/deg.mol. The most suitable length of glucan chain for branching was greater than 12 glucose units.
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PMID:A kinetic study of the interaction between glycogen and Neurospora crassa branching enzyme. 213 55

The nucleotide sequence of the Synechococcus sp. PCC7942 glgB gene has been determined. The gene contains a single open reading frame (ORF) of 2322 bp encoding a polypeptide of 774 amino acids (aa) with an Mr of 89,206. Extensive sequence similarity exists between the deduced aa sequence of the Synechococcus sp. glgB gene product and that of the Escherichia coli branching enzyme in the middle portions of the proteins (62% identical aa). In contrast, the N-terminal portions shared little homology. The sequenced region which follows glgB contains an ORF encoding 79 aa of the N terminus of a polypeptide that shares extensive sequence similarity (41% identical aa) with human and rat uroporphyrinogen decarboxylase. This suggests that the region downstream from glgB contains the hemE gene and, therefore, that the organization of genes involved in glycogen biosynthesis in Synechococcus sp. is different from that described for E. coli. A fusion gene was constructed between the 5' end of the Bacillus licheniformis penP gene and the Synechococcus sp. glgB gene. The fusion gene was efficiently expressed in the Gram+ micro-organism Bacillus subtilis and specified a branching enzyme with an optimal temperature for activity similar to the wild-type enzyme.
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PMID:Nucleotide sequence of the Synechococcus sp. PCC7942 branching enzyme gene (glgB): expression in Bacillus subtilis. 214 68

We describe the cloning of the r (rugosus) locus of pea (Pisum sativum L.), which determines whether the seed is round or wrinkled. Wrinkled (rr) seeds lack one isoform of starch-branching enzyme (SBEI), present in round (RR or Rr) seeds. A major polymorphism in the SBEI gene between near-isogenic RR and rr lines shows 100% cosegregation with the r locus, establishing that the SBEI gene is at the r locus. An aberrant transcript for SBEI is produced in rr embryos. In rr lines the SBEI gene is interrupted by a 0.8 kb insertion that is very similar to the Ac/Ds family of transposable elements from maize. Failure to produce SBEI has complex metabolic consequences on starch, lipid, and protein biosynthesis in the seed.
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PMID:The wrinkled-seed character of pea described by Mendel is caused by a transposon-like insertion in a gene encoding starch-branching enzyme. 215 53

Potato tubers are modified stems that have differentiated into storage organs. Factors such as day-length, nitrogen supply, and levels of the phytohormones cytokinin and gibberellic acid, are known to control tuberization. Morphological changes during tuber initiation are accompanied by the accumulation of a characteristic set of proteins, thought to be involved in N-storage (i.e. patatin) or defense against microbial or insect attack (i.e. proteinase inhibitor II). Additionally, deposition of large amounts of starch occurs during tuber formation, which is paralleled by an increase in sucrose synthase and other enzymes involved in starch biosynthesis (i.e. ADP-glucose pyrophosphorylase, starch synthases, and branching enzyme). Potential controlling mechanisms for genes expressed during tuberization are discussed.
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PMID:Gene expression during tuber development in potato plants. 220 Jul 13

Glycogen synthesis in rabbit muscle takes place on an autocatalytic protein that glucosylates itself to form a maltosaccharide that in turn primes the actions of glycogen synthase and branching enzyme to form glycogen. Here we show that in the form in which the protein is isolated from muscle it already contains one molecular proportion of a maltosaccharide ranging in length from 2 to 8 glucose residues. Self-glucosylation consists in the lengthening of all the chains to become malto-octaose.
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PMID:The biogenesis of glycogen: nature of the carbohydrate in the protein primer. 240 65

The reaction product of iodine and native glycogen or polyglucose synthesized histochemically by glycogen synthetase or phosphorylase with branching enzyme was studied in the paraboloid of the chick retina by light and electron microscopy. Native glycogen in the paraboloid stained brown, while histochemically synthesized polyglucose stained brown or purple. Electron microscopy revealed that the paraboloid in all experimental groups appeared to have many vacant spaces at the sites of polyglucose particles, as after the amylase digestion test. Native and histochemically synthesized polyglucose particles themselves looked like fine granules or appeared to have various densities in electron micrographs. These findings suggest that native or histochemically synthesized polyglucose particles are partly masked by the iodine atoms involved in the amylase channel in electron micrographs.
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PMID:Electron microscopic findings of polyglucose reacting with iodine. 241 60

Glycogen accumulation in Escherichia coli is inversely related to the growth rate and occurs most actively when cells enter the stationary phase. The levels of the three biosynthetic enzymes undergo corresponding changes under these conditions, suggesting that genetic control of enzyme biosynthesis may account for at least part of the regulation (J. Preiss, Annu. Rev. Microbiol. 38:419-458, 1984). We have begun to explore the molecular basis of this control by identifying factors which affect the expression of the glycogen genes and by determining the 5'-flanking regions required to mediate the regulatory effects. The in vitro coupled transcription-translation of two of the biosynthetic genes, glgC (ADPglucose pyrophosphorylase) and glgA (glycogen synthase), was enhanced up to 26- and 10-fold, respectively, by cyclic AMP (cAMP) and cAMP receptor protein (CRP). Guanosine 5'-diphosphate 3'-diphosphate stimulated the expression of these genes 3.6- and 1.8-fold, respectively. The expression of glgB (glycogen branching enzyme) was affected weakly or negligibly by the above-mentioned compounds. Assays which measured the in vitro formation of the first dipeptide of glgC showed that a restriction fragment which contained 0.5 kilobases of DNA upstream from the initiation codon supported cAMP-CRP-activated expression. Sequence-specific binding of cAMP-CRP to a 243-base-pair restriction fragment from the region upstream from glgC was observed by virtue of the altered electrophoretic mobility of the bound DNA. S1 nuclease protection analysis identified 5' termini of four in vivo transcripts within 0.5 kilobases of the glgC coding region. The relative concentrations of transcripts were higher in the early stationary phase than in the exponential phase. Two mutants which overproduced the biosynthesis enzymes accumulated elevated levels of specific transcripts. The 5' termini of three of the transcripts were mapped to a high resolution. Their upstream sequences showed weak similarity to the E. coli consensus promoter. These results suggest complex transcriptional regulation of the glycogen biosynthesis genes involving multiple promoter sites and direct control of gene expression by at least two global regulatory systems.
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PMID:Genetic regulation of glycogen biosynthesis in Escherichia coli: in vitro effects of cyclic AMP and guanosine 5'-diphosphate 3'-diphosphate and analysis of in vivo transcripts. 246 50

Although type IV glycogen storage disease (Andersen disease; McKusick 23250) is considered to be a rare, autosomally recessive disorder, of the more than 600 patients with glycogenosis identified in our laboratory by enzymatic assays, 6% have been shown to be deficient in the glycogen branching enzyme. Most of the 38 patients with type IV glycogen storage disease who are known to us have succumbed at a very early age, with the exception of one male teenager, an apparently healthy 7-year-old male, and several 5-year-old patients. Fourteen pregnancies at risk for branching enzyme deficiency have been monitored using cultured amniotic fluid cells, and four additional pregnancies have been screened using cultured chorionic villi. Essentially no branching enzyme activity was detectable in eight samples (amniocytes); activities within the control range were found in five samples (three amniocyte and two chorionic villi samples); and five samples appeared to have been derived from carriers. In two of the cases lacking branching enzyme activity, in which the pregnancies were terminated and fibroblasts were successfully cultured from the aborted fetuses, no branching enzyme activity was found. Another fetus, which was predicted by antenatal assay to be affected, was carried to term. Skin fibroblasts from this baby were deficient in branching enzyme. Pregnancies at risk for glycogen storage disease due to the deficiency of branching enzyme can be successfully monitored using either cultured chorionic villi or amniocytes.
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PMID:Branching enzyme activity of cultured amniocytes and chorionic villi: prenatal testing for type IV glycogen storage disease. 252 70


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