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)

A Mr 34,000 wall protein was isolated as a by-product of the purification of an endo-(1-3)-beta-glucanase from the culture filtrate of Candida albicans. The purified fraction contained no exo- or endo-beta-glucanase activity, and analysis by SDS poly-acrylamide gel electrophoresis (SDS-PAGE) showed one protein band at Mr 34,000. Analysis by gel filtration high performance liquid chromatography (HPLC) of reaction products from incubations of the protein fraction with laminarioligosaccharides of five glucosyl units or greater revealed a unique glucanosyl transferase activity. The enzyme specifically cleaved laminaribiaose (G2) from the reducing-end of a linear beta-(1-3)-glucan and transferred the remainder to another laminarioligosaccharide. The reaction with laminaripentaose (G5) produced G2 and a product eluting at the position of G8. Analysis of the latter transferase product by 13C- and 1H-nuclear magnetic resonance (NMR) spectroscopy shows it to be a branched molecule containing a beta-(1-3)-beta-(1-6)-branchpoint. It is suggested that the Mr 34,000 wall protein is a glucan branching enzyme, perhaps the key enzyme responsible for the transformation of the initial linear beta-(1-3)-glucan into the branched beta-(1-3)-beta-1-6)-glucan as found in the cell wall of C. albicans.
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PMID:A secreted beta-glucan-branching enzyme from Candida albicans. 168 40

Two molecular forms (BE-I and -II) of 1,4-alpha-glucan branching enzyme were purified from rat liver by affinity chromatography on glycogen-adipoyldihydrazide-Sepharose 4B and glycogen-ethylenediamine-Sepharose 4B, respectively, after hydrophobic chromatography on hexylamine-Sepharose 4B, as single proteins with the same molecular weight of 82,000 on SDS-polyacrylamide gel electrophoresis. By comparing their UV spectra and by RNA detection on polyacrylamide gels after electrophoresis, BE-I and -II were identified to be RNA associated and unassociated forms, respectively. The molecular weights of BE-I and -II estimated by Sephadex G-200 gel filtration were 91,000 and 98,000, respectively, indicating that both forms consist of a monomer. As Be-II had about half the specific activity of BE-I, the RNA component was not essential for the activity of the rat liver branching enzyme, and it was also dissociable from the protein component (BE-II) on polyacrylamide gel electrophoresis at pH 7.3, whereby BE-II showed a heterogeneity of at least three microspecies as revealed by protein staining as well as by activity staining of the gels. Using the antibody against BE-I, BE-I and -II were indistinguishable on immunodiffusion, and the activity inhibition rate of BE-II by the antibody was almost the same as that of BE-I if their specific activities are considered, indicating that the RNA component may have no effect on the enzyme-antibody reaction. Immunochemically no isoenzyme was detected for this enzyme in rat tissues.
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PMID:Purification of RNA associated and unassociated forms of 1,4-alpha-glucan branching enzyme from rat liver. 617 27

Developing wild-type pea embryos contain two major isoforms of starch synthase and two isoforms of starch-branching enzyme. One of the starch synthases and both starch-branching enzymes occur both in the soluble fraction and tightly bound to starch granules. The other starch synthase, which is very similar to the waxy proteins of other species, is exclusively granule-bound., It is inactive when solubilized in a native form from starch granules, but activity is recovered when the SDS-denatured protein is reconstituted from polyacrylamide gels. Evidence is presented which indicates that all of these proteins become incorporated within the structure of the granule as it grows. It is proposed that the granule-bound waxy protein is active in vivo at the granule surface, whereas the remaining proteins are active in the soluble fraction of the amyloplast. The proteins become trapped within the granule matrix as the polymers they synthesize crystallize around them, and they probably play no further part in polymer synthesis.
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PMID:Soluble isoforms of starch synthase and starch-branching enzyme also occur within starch granules in developing pea embryos. 822 Apr 72

Full-length cDNA for starch branching enzyme (SBE) II of potato was isolated and sequenced. In potato, similarly to most other investigated plants, the SBE-II isoform differs from SBE-I by having an acidic amino-terminal extension and a shorter carboxyterminus. Two forms of SBE-II, migrating as 98 and 95 kDa proteins in 6% SDS-polyacrylamide gels, were associated to tuber starch. The latter form was 16 amino acids shorter in the amino terminus. Transcript of SBE-II was present in leaf tissue, whereas significant expression was not seen in tubers. On the other hand, a significant amount of SBE-I transcript was detected in tuber tissue but not in leaves.
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PMID:Molecular cloning and characterization of starch-branching enzyme II from potato. 961 17

Adult snails synthesize in their albumen glands a polysaccharide which is composed exclusively of D- or D- and L-galactose (Gal) residues which are interglycosidically linked by 1 --> 3 and 1 --> 6 bonds. It is the only carbohydrate source for embryos and freshly hatched snails. Two galactosyltransferases are described in this study which are most likely involved in the biosynthesis of this polysaccharide. One identified in Helix pomatia acts on oligosaccharides and could be used to synthesize a tetrasaccharide when the branched trisaccharide D-Gal-beta-(1 --> 3)-[D-Galbeta-(1 --> 6)]-D-Galbeta-1 --> OMe was offered as acceptor. This enzyme, requiring Mg++-and Mn++-ions for activity, introduced a linear beta-(1 --> 6) linkage at the terminal non-reducing ends and was not detected in Biomphalaria glabrata. The other enzyme, which introduced beta-(1 --> 6) linkages at subterminal D-Gal residues, thus forming branching points in the polysaccharide, was found in H. pomatia, Arianta arbustorum and B. glabrata with comparable activities. With the enzyme preparation of H. pomatia, up to four D-Gal residues were introduced into vicinal positions, forming single-membered side chains, if a hexasaccharide with five linearly beta-(1 --> 3)-linked D-Gal residues was offered as a acceptor. The multiple-branched structure formed is typical for snail galactans, making this enzyme a prime candidate for the branching enzyme in galactan synthesis. The enzyme activity could be solubilized and purified by affinity chromatography. In SDS-polyacrylamide electrophoresis, the Helix-derived eluate displayed two bands (68, 37 kDa) and that of Biomphalaria five bands (68, 63, 17.5; 15; 13 kDa). The purified material showed only 8% of the total activity of the crude extracts, but it could be shown that a phosphatase present in the crude extract can degrade UDP formed in the transfer reaction and thus drive the reaction to completion.
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PMID:Galactan biosynthesis in snails: a comparative study of beta-(1--> 6) galactosyltransferases from Helix pomatia and Biomphalaria glabrata. 1119 66

The glycogen branching enzyme gene (glgB) from Pectobacterium chrysanthemi PY35 was cloned, sequenced, and expressed in Escherichia coli. The glgB gene consisted of an open reading frame of 2196bp encoding a protein of 731 amino acids (calculated molecular weight of 83,859Da). The glgB gene is upstream of glgX and the ORF starts the ATG initiation codon and ends with the TGA stop codon at 2bp upstream of glgX. The enzyme was 43-69% sequence identical with other glycogen branching enzymes. The enzyme is the most similar to GlgB of E. coli and contained the four regions conserved among the alpha-amylase family. The glycogen branching enzyme (GlgB) was purified and the molecular weight of the enzyme was estimated to be 84kDa by SDS-PAGE. The glycogen branching enzyme was optimally active at pH 7 and 30 degrees C.
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PMID:Cloning and characterization of the glycogen branching enzyme gene existing in tandem with the glycogen debranching enzyme from Pectobacterium chrysanthemi PY35. 1248 May 26

A gene (sll0158) putatively encoding a glycogen branching enzyme (GBE, E.C. 2.4.1.18) was cloned from Synechocystis sp. PCC6803, and the recombinant protein expressed and characterized. The PCR-amplified putative GBE gene was ligated into a pET-21a plasmid vector harboring a T7 promoter, and the recombinant DNA transformed into a host cell, E. coli BL21(DE3). The IPTG-induced enzymes were then extracted and purified using Ni-NTA affinity chromatography. The putative GBE gene was found to be composed of 2,310 nucleotides and encoded 770 amino acids, corresponding to approx. 90.7 kDa, as confirmed by SDS-PAGE and MALDI-TOF-MS analyses. The optimal conditions for GBE activity were investigated by measuring the absorbance change in iodine affinity, and shown to be pH 8.0 and 30 degrees in a 50 mM glycine-NaOH buffer. The action pattern of the GBE on amylose, an alpha-(1,4)-linked linear glucan, was analyzed using high-performance anion-exchange chromatography (HPAEC) after isoamylolysis. As a result, the GBE displayed alpha-glucosyl transferring activity by cleaving the alpha-(1,4)-linkages and transferring the cleaved maltoglycosyl moiety to form new alpha-(1,6)- branch linkages. A time-course study of the GBE reaction was carried out with biosynthetic amylose (BSAM; Mp approximately = 8,000), and the changes in the branch-chain length distribution were evaluated. When increasing the reaction time up to 48 h, the weight- and number-average DP (DPw and DPn) decreased from 19.6 to 8.7 and from 17.6 to 7.8, respectively. The molecular size (Mp, peak Mw approximately = 2.45-2.75 x 10(5)) of the GBE-reacted product from BSAM reached the size of amylose (AM) in botanical starch, yet the product was highly soluble and stable in water, unlike AM molecules. Thus, GBE-generated products can provide new food and non-food applications, owing to their unique physical properties.
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PMID:Heterologous expression and characterization of glycogen branching enzyme from Synechocystis sp. PCC6803. 1875 98

Despite numerous studies on shrunken endosperm mutants caused by either maternal tissues (seg) or kernel per se (sex) in barley, the molecular mechanism for all of the eight seg mutants (seg1-seg8) and some sex mutants is yet to be uncovered. In this study, we determined the amylose content, characterized granule-binding proteins, analyzed the expression of key genes involved in starch synthesis, and examined starch granule structure of both normal (Bowman and Morex) and shrunken endosperm (seg1, seg3, seg4a, seg4b, seg5, seg6, seg7, and sex1) barley accessions. Our results showed that amylose contents of shrunken endosperm mutants ranged from 8.9% (seg4a) to 25.8% (seg1). SDS-PAGE analysis revealed that 87 kDa proteins corresponding to the starch branching enzyme II (SBEII) and starch synthase II (SSII) were not present in seg1, seg3, seg6, and seg7 mutants. Real-time quantitative PCR (RT-qPCR) analysis indicated that waxy expression levels of seg1, seg3, seg6, and seg7 mutants decreased in varying degrees to lower levels until 27 days after anthesis (DAA) after reaching the peak at 15-21 DAA, which differed from the pattern of normal barley accessions. Further characterization of waxy alleles revealed 7 non-synonymous single nucleotide polymorphisms (SNPs) in the coding sequences and 16 SNPs and 8 indels in the promoter sequences of the mutants. Results from starch granule by scanning electron microscopy (SEM) indicated that, in comparison with normal barley accessions, seg4a, seg4b, and sex1 had fewer starch granules per grain; seg3 and seg6 had less small B-type granules; some large A-type granules in seg7 had a hollow surface. These results improve our understanding about effects of seg and sex mutants on starch biosynthesis and granule structure during endosperm development and provide information for identification of key genes responsible for these shrunken endosperm mutants.
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PMID:Characterization of shrunken endosperm mutants in barley. 2450 69