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:2.4.1.18 (branching enzyme)
628 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The possible involvement of potato (Solanum tuberosum L.) starch-branching enzyme I (PSBE-I) in the in vivo synthesis of phosphorylated amylopectin was investigated in in vitro experiments with isolated PSBE-I using 33P-labeled phosphorylated and 3H end-labeled nonphosphorylated alpha(1-->4)glucans as the substrates. From these radiolabeled substrates PSBE-I was shown to catalyze the formation of dual-labeled (3H/33P) phosphorylated branched polysaccharides with an average degree of polymerization of 80 to 85. The relatively high molecular mass indicated that the product was the result of multiple chain-transfer reactions. The presence of alpha(1-->6) branch points was documented by isoamylase treatment and anion-exchange chromatography. Although the initial steps of the in vivo mechanism responsible for phosphorylation of potato starch remains elusive, the present study demonstrates that the enzyme machinery available in potato has the ability to incorporate phosphorylated alpha(1-->4)glucans into neutral polysaccharides in an interchain catalytic reaction. Potato mini tubers synthesized phosphorylated starch from exogenously supplied 33PO43- and [U-14C]Glc at rates 4 times higher than those previously obtained using tubers from fully grown potato plants. This system was more reproducible compared with soil-grown tubers and was therefore used for preparation of 33P-labeled phosphorylated alpha(1-->4)glucan chains.
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PMID:Phosphorylated alpha(1-->4)Glucans as substrate for potato starch-branching enzyme I 966 29

Adult polyglucosan body disease (APBD) is a late-onset, slowly progressive disorder of the nervous system caused by glycogen branching enzyme (GBE) deficiency in a subgroup of patients of Ashkenazi Jewish origin. Similar biochemical finding is shared by glycogen storage disease type IV (GSD IV) that, in contrast to APBD, is an early childhood disorder with primarily systemic manifestations. Recently, the GBE cDNA was cloned and several mutations were characterized in different clinical forms of GSD IV. To examine whether mutations in the GBE gene account for APBD, we studied 7 patients from five Jewish families of Ashkenazi ancestry. The diagnosis was based on the typical clinical and pathological findings, and supported by reduced GBE activity. We found that the clinical and biochemical APBD phenotype in all five families cosegregated with the Tyr329Ser mutation, not detected in 140 controls. As this mutation was previously identified in a nonprogressive form of GSD IV and was shown in expression studies to result in a significant residual GBE activity, present findings explain the late onset and slowly progressive course of APBD in our patients. We conclude that APBD represents an allelic variant of GSD IV, but the reason for the difference in primary tissue involvement must be established.
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PMID:Adult polyglucosan body disease in Ashkenazi Jewish patients carrying the Tyr329Ser mutation in the glycogen-branching enzyme gene. 985 30

The nucleotide sequence containing the complete structural information for a glucan branching enzyme was isolated from a Neisseria denitrificans genomic library. The gene was expressed in Escherichia coli and the active recombinant protein was purified. The deduced protein of 762 amino acids with a calculated molecular weight of 86313 Da shows similarity to the primary protein sequences of other known glucan branching enzymes. Amino acid sequencing of the isolated protein by Edman degradation confirmed the deduced start codon of the structural gene of the glucan branching enzyme. The purified glucan branching enzyme has a stimulating effect on the Neisseria amylosucrase activity.
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PMID:Molecular cloning, functional expression and purification of a glucan branching enzyme from Neisseria denitrificans(1). 1040 63

Deficiency of glycogen branching enzyme activity causes glycogen storage disease type IV (GSD-IV). Clinically, GSD-IV has variable clinical presentations ranging from a fatal neonatal neuromuscular disease, to a progressive liver cirrhosis form, and to a milder liver disease without progression. Current methods for prenatal and postnatal diagnosis are based on an indirect method of measuring the enzyme activity, which has a limited sensitivity and cannot be used to distinguish patients with these variable clinical phenotypes. In this study, a GSD-IV family with a non-progressive hepatic form of the disease requested prenatal diagnosis. Determination of the branching enzyme activity in cultivated amniocytes showed 20 per cent residual activity overlapping with the level detected in the heterozygotes. Mutation analysis revealed that the fetus carried two mutant alleles, L224P and Y329S, the same as the proband of this family. The fetus was predicted to be affected and postnatally his clinical presentation is consistent with the diagnosis. We conclude that DNA mutation analysis should be used in the prenatal diagnosis of GSD-IV, especially in the situation of high residual enzyme activity.
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PMID:Prenatal diagnosis of glycogen storage disease type IV using PCR-based DNA mutation analysis. 1052 41

Glycogen storage disease type IV (GSD-IV) is a rare autosomal recessive disease caused by a deficiency of glycogen branching enzyme (GBE) activity. This results in the accumulation of abnormal glycogen in the liver and other organs. We report the case of a 14-month-old female patient with typical hepatic pathologic findings of GSD-IV. The patient suffered from decreased muscle tone and progressive hepatosplenomegaly since birth. A wedge biopsy of the liver showed enlarged hepatocytes with colorless to faintly eosinophilic ground glass intracytoplasmic inclusions. Portal fibrosis and lobular, fibrous septa were present. Ultrastructure of the inclusions revealed non-membrane-bound fibrillar material 5 nm in maximal diameter. Enzyme study revealed a total deficiency of GBE activity.
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PMID:Glycogen storage disease type IV: a case report. 1053 7

We have identified a novel missense mutation in the gene for glycogen branching enzyme (GBE 1) in a 16-month-old infant with a combination of hepatic and muscular features, an atypical clinical presentation of glycogenosis type IV (GSD IV). The patient was heterozygous for a G-to-A substitution at codon 524 (R524Q), changing an encoded arginine (CGA) to glutamine (CAA), while the GBE1 gene on the other allele was not expressed. This case broadens the spectrum of mutations in patients with GSD IV and confirms the clinical and molecular heterogeneity of this disease.
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PMID:A novel missense mutation in the glycogen branching enzyme gene in a child with myopathy and hepatopathy. 1054 44

Branching enzyme from Escherichia coli is shown to be inhibited by the pseudooligosaccharide BAY e4609. The mechanism of binding is studied in detail by kinetics using reduced amylose as substrate. Lineweaver-Burk plots suggest the mechanism of a noncompetitive or slow-binding inhibitor. Further studies by progress curves and rate of loss of branching activity allows us to conclude BAY e4609 as being a slow-binding inhibitor of branching enzyme. We discuss how these results parallel the inhibition of alpha-amylase by acarbose and the significance of branching enzyme as belonging to the amylolytic family.
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PMID:Slow-binding inhibition of branching enzyme by the pseudooligosaccharide BAY e4609. 1064 Mar 98

There are 11 glycogen diseases (GSD), nine of which are associated with myopathy. Most of these glycogen storage myopathies are associated with dynamic symptoms and signs in that the major neuromuscular complaints are exercise-induced muscle pain, cramps, and myoglobinura (e.g., GSD V or McArdle's disease associated with myophosphorylase deficiency). The other types of glycogen storage myopathies are considered static in that they are associated with fixed weakness rather than dynamic symptoms and signs. The static glycogen storage myopathies include: GSD I or Pompe's disease (acid maltase or (-glucosidase deficiency), GSD II or Cori-Forbes disease (debranching enzyme deficiency), and GSD IV or Andersen's disease (branching enzyme deficiency). This article reviews the clinical, laboratory, electrophysiologic, histopathologic, and pathogenesis of these static GSD myopathies.
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PMID:Acid maltase deficiency and related myopathies. 1065 72

A 6-kb DNA fragment of the Rhodobacter sphaeroides 2.4.1 glg operon was cloned from a genomic library using a polymerase chain reaction probe coding for part of the ADP-glucose pyrophosphorylase (glgC) gene. The DNA fragment was sequenced and found to harbor complete open reading frames for the glgC and glgA (glycogen synthase) genes and partial sequences corresponding to glgP (glycogen phosphorylase) and glgX (glucan hydrolase/transferase) genes. The genomic fragment also contained an apparent truncated sequence corresponding to the C-terminus of the glgB gene (branching enzyme). The presence of active branching enzyme activity in crude sonicates of Rb. sphaeroides cells indicates that the genome contains a full-length glgB at another location. The structure of this operon in relation to other glg operons is further discussed. The deduced sequence of the ADP-glucose pyrophosphorylase enzyme is compared to other known ADP-glucose pyrophosphorylase sequences and discussed in relation to the allosteric regulation of this enzyme family. The glgC gene was subcloned in the vector pSE420 (Invitrogen) for high-level expression in E. coli. The successful overexpression of the recombinant enzyme allowed for the purification of over 35 mg of protein from 10 g of cells, representing a dramatic improvement over enzyme isolation from the native strain. The recombinant enzyme was purified to near homogeneity and found to be physically, immunologically, and kinetically identical to the native enzyme, verifying the fidelity of the cloning step.
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PMID:Cloning and sequencing of glycogen metabolism genes from Rhodobacter sphaeroides 2.4.1. Expression and characterization of recombinant ADP-glucose pyrophosphorylase. 1072 89

We describe the first non-Ashkenazi patient with adult polyglucosan body disease and decreased glycogen-branching enzyme (GBE) activity in leukocytes. Gene analysis revealed compound heterozygosity for two novel missense mutations Arg515His and Arg524Gln in the GBE gene. Both missense mutations are predicted to impair GBE activity. This is the first identification of GBE mutations underlying adult polyglucosan body disease in a non-Ashkenazi family, and confirms that adult glycogen storage disease type IV can manifest clinically as adult polyglucosan body disease.
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PMID:Novel missense mutations in the glycogen-branching enzyme gene in adult polyglucosan body disease. 1076 70


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