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 transglycosylation reaction catalyzed by neopullulanase was analyzed. Radioactive oligosaccharides were produced when the enzyme acted on maltotriose in the presence of [U-14C]glucose. Some of the radioactive oligosaccharides had only alpha-(1----4)-glucosidic linkages, but others were suggested to have alpha-(1----6)-glucosidic linkages. The existence of alpha-(1----6)-glucosidic linkages in the products from maltotriose with neopullulanase was proven by proton NMR spectroscopy and methylation analysis. We previously reported that the one active center of neopullulanase catalyzes the hydrolysis of alpha-(1----4)- and alpha-(1----6)-glucosidic linkages (Kuriki, T., Takata, H., Okada, S., and Imanaka, T. (1991) J. Bacteriol. 173,6147-6152). These facts proved that neopullulanase catalyzed all four types of reactions: hydrolysis of alpha-(1----4)-glucosidic linkage, hydrolysis of alpha-(1----6)-glucosidic linkage, transglycosylation to form alpha-(1----4)-glucosidic linkage, and transglycosylation to form alpha-(1----6)-glucosidic linkage. The four reactions are typically catalyzed by alpha-amylase, pullulanase, cyclomaltodextrin glucanotransferase, and 1,4-alpha-D-glucan branching enzyme, respectively. These four enzymes have some structural similarities to one other, but reactions catalyzed by the enzymes are considered to be distinctive: the four reactions are individually catalyzed by each of the enzymes. The experimental results obtained from the analysis of the reaction of the neopullulanase exhibited that the four reactions can be catalyzed in the same mechanism.
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PMID:Action of neopullulanase. Neopullulanase catalyzes both hydrolysis and transglycosylation at alpha-(1----4)- and alpha-(1----6)-glucosidic linkages. 138 53

Activities of glycogen synthase (total) and branching enzyme in slow (soleus) muscle are higher than those in fast (vastus lateralis) muscle, while those of phosphorylase kinase (total), phosphorylase (total) and debranching enzyme are reversed. The active form ratio of glycogen synthase is higher in fast muscle, while those of phosphorylase kinase and phosphorylase are higher in slow muscle. Activities of cAMP-dependent protein kinase and protein phosphatase in slow muscle are higher than those in fast muscle. These results suggest that glycogen metabolizing enzymes in slow muscle, distinct from those in fast muscle, are regulated more strongly by cAMP-dependent protein kinase rather than by protein phosphatase.
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PMID:Comparison of enzyme activities on glycogen metabolism in rabbit slow and fast muscles. 299 76

Type IV glycogenosis is due to branching enzyme deficiency and is usually manifested clinically by progressive liver disease with cirrhosis and hepatic failure between the second and fourth years of life. We describe a 5-year-old boy who, following an acute febrile illness at 2 years of age, was first noted to have hepatomegaly with mildly elevated serum transaminase levels. Liver biopsy revealed hepatic fibrosis with periodic-acid Schiff-positive, diastase-resistant inclusions in hepatocytes and fibrillar inclusions characteristic of amylopectin by electron microscopy. Enzymatic assay revealed deficient hepatic branching enzyme activity with normal activity of glucose-6-phosphatase, debranching enzyme and phosphorylase activities. During the succeeding 3 years, he grew and developed normally with apparent resolution of any clinical evidence of liver disease and only intermittent elevation in serum transaminase levels associated with fever and prolonged fasting. Repeat liver biopsy at 4 years of age showed persistence of scattered hepatocellular periodic-acid Schiff-positive, diastase-resistant inclusions, but no progression of hepatic fibrosis in spite of persistent deficiency of hepatic branching enzyme activity. Skeletal muscle and skin fibroblasts from the patient also showed deficient enzyme activity. Skin fibroblasts from both parents exhibited half the normal control activity, suggesting a heterozygote state. This is the first documented patient with deficiency of branching enzyme but without evidence of progressive hepatic disease. This patient, coupled with reports of other patients with late onset hepatic or muscle disease with branching enzyme deficiency, suggests that the defect resulting in Type IV glycogen storage disease is more heterogenous and possibly more common than previously suspected.
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PMID:A new variant of type IV glycogenosis: deficiency of branching enzyme activity without apparent progressive liver disease. 316 25

The mechanism of action of liver branching enzyme has been studied by using as substrate two polysaccharides in which the non-reducing ends had been labelled by incubation with phosphorylase and a trace amount of [(14)C]glucose 1-phosphate. After these polysaccharides had been treated with branching enzyme, their structure was analysed by periodate oxidation, by degradation with phosphorylase and amylo-(1-->6)-glucosidase and by degradation with pullulanase. All the results indicate that the branching enzyme catalyses the transfer from (1-->4)- to (1-->6)-linkage of a chain of glucose units, the minimum length of which is six glucose units. A maltodextrin containing 16 glucose units was not acted on by the branching enzyme.
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PMID:A study of the reaction catalysed by the liver branching enzyme. 429 May 51

1. Pullulanase synthesis was studied in 16 classified (N.C.I.B.) strains and in an industrial strain (R) of Klebsiella aerogenes grown in chemostats containing maltose as inducer and sole carbon source. 2. Maximum synthesis was associated with carbon-limited growth at a low dilution rate (about 0.2h(-1)). The enzyme remained firmly cell-bound and seemed to be located on the cell surface. 3. Three strains had high activity (R, N.C.I.B. 5938, 8017), twelve were intermediate, and two (N.C.I.B. 8153, 9146) had negligible activity but were inducible with pullulan. 4. Pullulan similarly induced low, but adequate, activity in the other strains in conditions (nutrient limitation other than carbon-limitation) in which pullulanase was otherwise very seriously repressed. Nevertheless, in carbon limitation pullulan induced no more enzyme than did maltose, maltotriose or oligosaccharide mixtures, and ;hyperactivity' never developed on protracted culture. 5. Cyclic AMP relieved the transient repression produced by adding glucose to maltose-limited cultures and a further change to glucose-limited conditions led to constitutive pullulanase synthesis. 6. Amylomaltase and alpha-glucosidase activities were also examined but in less detail. 7. The presence of pullulanase in maltose-limited growth is discussed, but no clear function can be assigned to it at present. The molar growth yields for all the strains were very similar, and no correlation was found between the overgrowth of one strain by another and pullulanase activity. Further, any function as a general branching enzyme in polysaccharide synthesis seems unlikely.
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PMID:Pullulanase synthesis in klebsiella (aerobacter) aerogenes strains growing in continuous culture. 437 62

High glycogen content and abnormal mitochondria have been seen in muscles from RN- carrier pigs in a previous work. Glycogen synthase, branching enzyme, phosphorylase and debranching enzyme activities, and mitochondrial characteristics were studied in normal and RN- carrier pigs. Branching enzyme activity was higher (P < 0.01) and glycogen synthase activity tended to be higher in longissimus dorsi muscle from RN- carrier pigs compared to normal pigs. There were no differences in the activities of either phosphorylase and debranching enzyme between both types of pigs. Citrate synthase activity and mitochondrial respiration were slightly higher in muscle from RN- pigs compared to normal pigs. Glycogen content in muscle from RN- pigs could result from the imbalance between anabolic and catabolic enzyme activities of glycogen metabolism. The higher specific activity in mitochondria of RN- pigs muscle might be the compensatory effect of an abnormal glycolytic metabolism.
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PMID:Enzyme activities of glycogen metabolism and mitochondrial characteristics in muscles of RN- carrier pigs (Sus scrofa domesticus). 808 56

Sequence alignment and structure prediction are used to locate catalytic alpha-amylase-type (beta/alpha)8-barrel domains and the positions of their beta-strands and alpha-helices in isoamylase, pullulanase, neopullulanase, alpha-amylase-pullulanase, dextran glucosidase, branching enzyme, and glycogen branching enzymes--all enzymes involved in hydrolysis or synthesis of alpha-1,6-glucosidic linkages in starch and related polysaccharides. This has allowed identification of the transferase active site of the glycogen debranching enzyme and the locations of beta-->alpha loops making up the active sites of all enzymes studied. Activity and specificity of the enzymes are discussed in terms of conserved amino acid residues and loop variations. An evolutionary distance tree of 47 amylolytic and related enzymes is built on 37 residues representing the four best conserved beta-strands of the barrel. It exhibits clusters of enzymes close in specificity, with the branching and glycogen debranching enzymes being the most distantly related.
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PMID:Starch- and glycogen-debranching and branching enzymes: prediction of structural features of the catalytic (beta/alpha)8-barrel domain and evolutionary relationship to other amylolytic enzymes. 813 30

In the developing endosperm of monocotyledonous plants, starch granules are synthesized and deposited within the amyloplast. A soluble stromal fraction was isolated from amyloplasts of immature maize (Zea mays L.) endosperm and analyzed for enzyme activities and polypeptide content. Specific activities of starch synthase and starch-branching enzyme (SBE), but not the cytosolic marker alcohol dehydrogenase, were strongly enhanced in soluble amyloplast stromal fractions relative to soluble extracts obtained from homogenized kernels or endosperms. Immunoblot analysis demonstrated that starch synthase I, SBEIIb, and sugary1, the putative starch-debranching enzyme, were each highly enriched in the amyloplast stroma, providing direct evidence for the localization of starch-biosynthetic enzymes within this compartment. Analysis of maize mutants shows the deficiency of the 85-kD SBEIIb polypeptide in the stroma of amylose extender cultivars and that the dull mutant lacks a >220-kD stromal polypeptide. The stromal fraction is distinguished by differential enrichment of a characteristic group of previously undocumented polypeptides. N-terminal sequence analysis revealed that an abundant 81-kD stromal polypeptide is a member of the Hsp70 family of stress-related proteins. Moreover, the 81-kD stromal polypeptide is strongly recognized by antibodies specific for an Hsp70 of the chloroplast stroma. These findings are discussed in light of implications for the correct folding and assembly of soluble, partially soluble, and granule-bound starch-biosynthetic enzymes during import into the amyloplast.
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PMID:Polypeptides of the maize amyloplast stroma. Stromal localization of starch-biosynthetic enzymes and identification of an 81-kilodalton amyloplast stromal heat-shock cognate. 953 63

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

Biochemical analysis of amylose-extender (ae) mutant of rice (Oryza sativa) revealed that the mutation in the gene for starch-branching enzyme IIb (BEIIb) specifically altered the structure of amylopectin in the endosperm by reducing short chains with degree of polymerization of 17 or less, with the greatest decrease in chains with degree of polymerization of 8 to 12. The extent of such change was correlated with the gelatinization properties of the starch granules, as determined in terms of solubility in urea solution. The ae mutation caused a dramatic reduction in the activity of BEIIb. The activity of soluble starch synthase I (SSI) in the ae mutant was significantly lower than in the wild type, suggesting that the mutation had a pleiotropic effect on the SSI activity. In contrast, the activities of BEI, BEIIa, ADP-Glc pyrophosphorylase, isoamylase, isoamylase, pullulanase, and Suc synthase were not affected by the mutation. Therefore, it is stressed that the function of BEIIb cannot be complemented by BEIIa and BEI. These results strongly suggest that BEIIb plays a specific role in the transfer of short chains, which might then be extended by SS to form the A and B(1) chains of amylopectin cluster in rice endosperm.
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PMID:Biochemical and genetic analysis of the effects of amylose-extender mutation in rice endosperm. 1159 21


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