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The effect of new alpha-glucosidase inhibitors (BAY m 1099 and BAY o 1248) on meal-stimulated increases in glucose and insulin levels in man.

To confirm findings obtained from animal experiments demonstrating the metabolic effect of two new glucosidase inhibitors, 7 single blind cross-over studies with 42 healthy male volunteers were performed. In each group 6 subjects received 25, 50, 100 and 200 mg BAY m 1099 and 10, 20, and 40 mg BAY o 1248 or placebo with a standardized breakfast. Blood glucose and serum insulin were measured in venous blood before and 30, 60, 90, 120 and 180 min after each of 3 meals. ECG, blood pressure, body weight, monitor ECG and haematological and clinico-chemical parameters were also examined. The postprandial increase in blood glucose and serum insulin after breakfast were significantly and dose-dependently reduced by BAY m 1099. 10 and 20 mg BAY o 1248 not only reduced the increases in blood glucose and serum insulin after breakfast, but also after lunch (10 mg). 40 mg BAY o 1248 prevented the postprandial increase in both metabolic parameters after breakfast (p less than 0.05), an effect which was sustained after lunch. Intestinal problems occurred (flatulence, meteorism, diarrhoea) in 25 of 42 volunteers. Objective tolerability was good. The results of these first clinical pharmacological studies with two new glucosidase inhibitors justify studies on patients with diabetes mellitus.

1-Deoxynojirimycin↗

Zinc can activate cellular acidic alpha-D-glucosidase activity.

In an attempt to elucidate the effect of metallic ions and EDTA on acidic alpha-D-glucosidase activity, we measured acidic alpha-D-glucosidase activity from either lymphocyte and muscle tissue homogenates or intact cells after incubation with metallic ions. The results showed that this enzyme activity was strongly inhibited by Ag+, Hg2+, and Fe3+ in either lymphocyte or muscle tissue homogenates. There was no effect of Zn2+, Cu2+, and Cd2+. However, intact cells, either lymphocyte or muscle cells, after incubation with Zn2+ for 1 or 2 hr, showed enhanced enzyme activity and suppression in the other metallic ion groups, especially in Ag+, Hg2+, and Fe3+. Since deficiency of this enzyme can cause type II glycogen storage disease (Pompe's disease), the more we understand the character of this enzyme, the more we can improve our enzymatic therapy.

Cations↗

Immobilized beta-glucosidase from Curvularia lunata.

beta-Glucosidase from Curvularia lunata was immobilized in pellets of polyacrylamide, sodium alginate and agar. The activity of the enzyme was estimated at different times by measuring the absorbance of a solution into which 2-nitrophenol was released by the enzyme. The effect of pH and temperature was studied to select the optimum conditions. Thermostability of the beta-glucosidase in each of the carriers was assessed over a period of 12-26 d. The immobilized enzyme on all the three carriers retained its activity longer than free enzyme did. Polyacrylamide was the best carrier both in terms of thermostability and of reusability of the immobilized enzyme preparations. The Michaelis constant (Km) for each of the immobilized enzyme preparation was calculated.

Enzyme Stability↗

Purification and characterization of a beta-glucosidase from Aspergillus niger.

The high-molar mass form of beta-glucosidase from Aspergillus niger strain NIAB280 was purified to homogeneity with a 46-fold increase in purification by a combination of ammonium sulfate precipitation, hydrophobic interaction, ion-exchange and gel-filtration chromatography. The native and subunit molar mass was 330 and 110 kDa, respectively. The pH and temperature optima were 4.6-5.3 and 70 degrees C, respectively. The K(m) and kcat for 4-nitrophenyl beta-D-glucopyranoside at 40 degrees C and pH 5 were 1.11 mmol/L and 4000/min, respectively. The enzyme was activated by low and inhibited by high concentrations of NaCl. Ammonium sulfate inhibited the enzyme. Thermolysin periodically inhibited and activated the enzyme during the course of reaction and after 150 min of proteinase treatment only 10% activity was lost with concomitant degradation of the enzyme into ten low-molar-mass active bands. When subjected to 0-9 mol/L transverse urea-gradient-PAGE for 105 min at 12 degrees C, the nonpurified beta-glucosidase showed two major bands which denatured at 4 and 8 mol/L urea, respectively, with half-lives of 73 min.

Ammonium Sulfate↗

Isolation and characterization of two forms of beta-D-glucosidase from Aspergillus niger.

beta-D-glucosidase purified from commercial preparations of clarified culture broth of Aspergillus niger (Novo SP188) was shown to elute as two distinct species during analytical anion-exchange chromatography (AEC). However, the two enzyme forms behaved identically on sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE), high-performance size-exclusion chromatography (HPSEC), and isoelectric focusing. Also, the N-terminal amino acid sequence, amino acid composition, fingerprint of tryptic-digest peptides, circular dichroism spectra, and reaction kinetics appear identical for these forms. This feature of the A. niger enzyme is distinctly different from beta-D-glucosidase isozymes reported from other sources, where multiple forms tend to differ in molecular weight and/or isoelectric pH. Michaelis-Menten kinetic analysis also gave comparable results for the two forms. The distinct behavior on AEC was explained by considering the differences in N-linked carbohydrates liberated from both species following treatment with endoglycosidase H or F.

Amino Acid Sequence↗

Oligo-1,6-glucosidase and neopullulanase enzyme subfamilies from the alpha-amylase family defined by the fifth conserved sequence region.

The alpha-amylase enzyme family is the largest family of glycoside hydrolases. It contains almost 30 different enzyme specificities covering hydrolases, transferases and isomerases. Some of the enzyme specificities from the family are closely related, others less so. This study, based on the analysis of 79 amino acid sequences, postulates two subfamilies in the framework of the aamylase family: the oligo-1,6-glucosidase subfamily and the neopullulanase subfamily. The specific sequence in the fifth conserved sequence region of the family served as the basis for defining the subfamilies: QpDln for the oligo-1,6-glucosidase subfamily and MPKln for the neopullulanase subfamily. This conserved sequence region is proposed to be the selection marker that enables one to distinguish between the two subfamilies. The 'intermediary' sequence MPDLN can be characteristic of the so-called intermediary group with a mixed enzyme specificity of alpha-amylase, cyclomaltodextrinase and neopullulanase. The evolutionary trees clearly supported the proposed definition of the two subfamilies.

Amino Acid Sequence↗

Assay for determination of alpha-glucosidase and peptidase activity and location in a nitrifying trickling filter.

Enzymatic alpha-glucosidase and peptidase activity in a nitrifying trickling filter (NTF) at the Rya wastewater treatment plant, Göteborg, Sweden, was investigated to evaluate whether these activities can be used as indicators of heterotrophic activity and polymer degradation. Samples of the biofilm were taken from the NTF and incubated in sterile filtered effluent water from the NTF with the addition of soluble starch, peptone, and ammonium chloride. In order to determine the distribution of enzyme activities, the alpha-glucosidase and peptidase activities were measured in the biofilm samples, in the filtered effluent water from the NTF and in the water phase in which the biofilm was incubated. Activities of both enzymes were found both in the effluent water from the NTF and in the biofilm. The enzyme activities were elevated in the samples when starch and peptone were present. In addition, there was a significant inhibition of ammonium oxidation in samples incubated with starch and peptone. Thus, the presence of starch, peptone and ammonium resulted in increased activity of heterotrophs, which lead to an inhibition of the nitrifiers, probably via competition for available oxygen.

Ammonia↗

A novel beta-glucosidase in Uromyces fabae: feast or fight?

Efficient nutrient mobilization is a key element for biotrophic plant parasites such as the rust fungi. In the course of a cDNA library screen for elements involved in sugar utilization in Uromyces fabae, we identified a sequence with homology to beta-glucosidases. Full-length genomic and cDNA clones of the gene, termed BGL1, were isolated and sequenced. The BGL1 gene comprises 3,372 nucleotides, including nine introns. The open reading frame encompasses 2,532 bases and codes for a polypeptide of 843 amino acids with an apparent molecular mass of 92.4 kDa. Analysis of the polypeptide revealed a potential secretion signal, indicating an extracellular localization of mature BGL1p (89.8 kDa). BGL1 seems to be expressed in all stages of growth, including haustoria, the feeding structures of rust fungi. In the course of immunolocalization studies, the gene product BGL1p was localized in the periphery of intercellular hyphae and haustoria. On the basis of sequence homology, the BGL1 gene was identified as a fungal beta-glucosidase.

Amino Acid Sequence↗

Expression and secretion of the Candida wickerhamii extracellular beta-glucosidase gene, bglB, in Saccharomyces cerevisiae.

The yeast Candida wickerhamii exports a cell-associated beta-glucosidase that is active against cellobiose and all soluble cellodextrins. Because of its unique ability to tolerate end-product inhibition by glucose, the bglB gene that encodes this enzyme was previously cloned and sequenced in this laboratory. Using several different promoters and constructs, bglB was expressed in the hosts Escherichia coli, Pichia pastoris, and Saccharomyces cerevisiae. Expression was initially performed in E. coli using either the lacZ or tac promoter. This resulted in intracellular expression of the BglB protein with the protein being rapidly fragmented. Secretion and glycosylation of active beta-glucosidase was achieved with several different S. cerevisiae constructs utilizing either the adh1 or the gal1 promoter on 2-micro replicating plasmids. When either the invertase (Suc2) or the BglB secretion signal was used, BglB protein remained associated with the cell wall and appeared to be hyperglycosylated. Expression in P. pastoris was also examined to determine if higher activity and expression could be achieved in a yeast host that usually does not hyperglycosylate. Using the alcohol oxidase promoter in conjunction with either the pho1 or the alpha-factor secretion signal, the recombinant enzyme was successfully secreted and glycosylated in P. pastoris. However, levels of protein expression from the chromosomally integrated vector were insufficient to detect activity.

Alcohol Oxidoreductases↗

Expression, purification and characterization of a recombinant beta-glucosidase from Volvariella Volvacea.

For the first time, a beta-glucosidase gene from the edible straw mushroom, Volvariella volvacea V1-1, has been over-expressed in E. coli. The gene product was purified by chromatography showing a single band on SDS-PAGE. The recombinant enzyme had a molecular mass of 380 kDa with subunits of 97 kDa. The maximum activity was at pH 6.4 and 50 degrees C over a 5 min assay. The purified enzyme was stable from pH 5.6-8.0, had a half life of 1 h at 45 degrees C. The beta-glucosidase had a K(m) of 0.2 mM: for p-nitrophenyl-beta-D: -glucopyranoside.

Agaricales↗

Acid alpha-glucosidase deficiency (Pompe disease).

The development and recent approval of recombinant acid alpha-glucosidase for enzyme replacement therapy have been major milestones in Pompe disease research. Acid alpha-glucosidase is the enzyme responsible for degradation of glycogen polymers to glucose in the acidic milieu of the lysosomes. Cardiac and skeletal muscles are the two major tissues affected by the accumulation of glycogen within the lysosomes. Both cardiomyopathy and skeletal muscle myopathy are observed in patients with complete enzyme deficiency; this form of the disease is fatal within the first year of life. Skeletal muscle myopathy eventually leading to respiratory insufficiency is the predominant manifestation of partial enzyme deficiency. The recombinant enzyme alglucosidase alfa is the first drug ever approved for this devastating disorder. This review discusses the benefits and the shortcomings of the new therapy.

Animals↗

A molecular and biochemical analysis of the structure of the cyanogenic beta-glucosidase (linamarase) from cassava (Manihot esculenta Cranz).

The cyanogenic beta-glucosidase (linamarase) of cassava is responsible for the first step in the sequential break-down of two related cyanoglucosides. Hydrolysis of these cyanoglucosides occurs following tissue damage and leads to the production of hydrocyanic acid. This mechanism is widely regarded as a defense mechanism against predation. A linamarase cDNA clone (pCAS5) was isolated from a cotyledon cDNA library using a white clover beta-glucosidase heterologous probe. The nucleotide and derived amino acid sequence is reported and five putative N-asparagine glycosylation sites are identified. Concanavalin A affinity chromatography and endoglycosidase H digestion demonstrate that linamarase from cassava is glycosylated, having high-mannose-type N-asparagine-linked oligosaccharides. Consistent with this structure and the extracellular location of the active enzyme is the identification of an N-terminal signal peptide on the deduced amino acid sequence of pCAS5.

Amino Acid Sequence↗

Studies on almond emulsin beta-D-glucosidase. I. Isolation and characterization of a bifunctional isozyme.

A beta-D-glucosidase (beta-D-glucoside glucohydrolase, EC 3.2.1.21) isozyme has been isolated from almond emulsin. The isolated enzyme is a glycoprotein and migrates as a single band on Sephadex G-200 filtration, CM 52 ion exchange chromatography, polyacrylamide gel electrophoresis, sodium dodecyl sulfate polyacrylamide gel electrophoresis and isoelectric focussing. The glucosidase and galactosidase activities traverse together during Sephadex G-200 gel filtration. Polyacrylamide gels stained specifically for the 2 enzymes reveal that the two activities comigrate. The molecular weight of the isozyme has been found to be 135 180 +/- 770, and that of its protomers to be 65 150 +/- 650.

Glucosidases↗

Uptake by neuroblastoma cells of glucosylceramide, glucosylceramide glucosidase, its stimulator protein, and phosphatidylserine.

Serum-free cultured neuroblastoma cells (clone NlE-115) have been shown to absorb emulsified glucosylceramide, glucosylceramide glucosidase, an activator protein for the enzyme, and phosphatidylserine from a synthetic medium. Uptake of the enzyme was augmented by phosphatidylserine, and vice versa. Uptake of the enzyme-lipid complex was further augmented by the activator protein. It appears likely that the activator forms a complex only with the enzyme-lipid complex, not with the individual components. Two uptake mechanisms for the enzyme seem to be involved, one of which (the complex with activator proteins and acidic lipid) is sensitive to mannosyl phosphate groups. Hydrolysis of absorbed glucosylceramide was slow unless the medium was supplemented with the acidic phospholipid or glucosidase. The most rapid disappearance of stored glycolipid took place when the ternary mixture was added to the cell medium, enzyme + activator protein + phosphatidylserine. These findings may be relevant to enzyme replacement therapy for Gaucher disease.

Animals↗

Synthesis and use of novel fluorescent glycosphingolipids for estimating beta-glucosidase activity in vitro in the absence of detergents and subtyping Gaucher disease variants following administration into intact cells.

Two novel fluorescent glycolipids, LRO-glucosylceramide (LRO-GC) and LRO-trihexosylceramide (LRO-THC) were synthesized and utilized for estimating activities of the lysosomal, acid beta-glucosidase in cell extracts and intact skin fibroblasts, derived from normal individuals and patients with Gaucher disease subtypes. The uniqueness of the glycolipids is the fact that a fluorescent probe (lissamine rhodamine) is linked in a sulfonylamide linkage to the sphingosyl residue of the sphingolipid. Thus, the product of enzymatic hydrolysis, lissamine rhodamine sulfonylamido sphingosine (LRO-ceramide) cannot be further hydrolyzed and remains a metabolic end product. A unique property of LRO-GC as a substrate for the lysosomal, acid beta-glucosidase in vitro was the observation that enzymatic hydrolysis occurs in the absence of detergents and that hydrolytic rates are, in fact, reduced in the presence of Triton X-100 and/or sodium taurocholate. Also, both glycolipids penetrated the membrane of intact fibroblasts in the absence of serum and were hydrolyzed in lysosomes of the intact cells. The rates of intracellular hydrolysis decreased with the severity of the Gaucher disease subtypes. Using LRO-THC as substrate, the intracellular ratio of LRO-ceramide to LRO-glucosylceramide was an indicator for the specific GD-subtype.

Cells, Cultured↗

Novel structures of N-linked high-mannose type oligosaccharides containing alpha-D-galactofuranosyl linkages in Aspergillus niger alpha-D-glucosidase.

Seven oligosaccharides were isolated from alpha-D-glucosidase (EC 3.2.1.20) from Aspergillus niger, and the structures of these oligosaccharides were studied by 1H NMR spectroscopy. After treatment of the alpha-D-glucosidase with N-glycosidase F, seven major oligosaccharide peaks were detected by Dionex anion-exchange HPLC. The structures corresponding to the three peaks OS-1, OS-2, and OS-4 were determined to be Man8GlcNAc2, Man9GlcNAc2, and GlcMan9GlcNAc2, respectively, from 1H NMR spectra of the isolated fractions. Each of the four oligosaccharides OS-5, OS-6, OS-7-1, and OS-7-2 contained an alpha-D-galactofuranosyl residue (Galf) linked to Man(A) via an alpha-(1-->2)-linkage. OS-7 was found to consist of two oligosaccharides. The structures of these four oligosaccharides were determined to be GalfMan5GlcNAc2, GalfMan6GlcNAc2, GalfMan7GlcNAc2, and GalfMan8GlcNAc2 by 1H NMR spectroscopy and compositional analysis. The Galf structure of GalfMan5GlcNAc2 was found to be identical to that of an oligosaccharide previously isolated from the alpha-D-galactosidase of the same strain. The structure of OS-3 remains undetermined.

Aspergillus niger↗

Properties of the alpha-glucosidase from various human tissues in relation to glycogenosis type II (Pompe's disease).

The physico-chemical and electrophoretical properties of alpha-glucosidases from various human tissues and urine have been studied. There were some differences among Peak I enzymes (neutral alpha-glucosidases) obtained from liver, heart, muscle, kidney and urine. These differences are based on different effects of tris(hydroxymethyl)aminomethane and various thermostabilities of the Peak I enzymes. Electrophoretically, the Peak I enzyme activity at pH 6.5 from control tissues displayed a two-banded pattern except in kidney and urine. In the patient with the adult form of Pompe's disease the faster band of the Peak I enzyme from heart and muscle was not found and the slower band of the Peak I enzyme from liver was more cathodic. The results are discussed in relation to glycogenosis type II (Pompe's disease).

Copper↗

Overproduction, purification and crystallization of Bacillus cereus oligo-1,6-glucosidase.

The gene coding for oligo-1,6-glucosidase from Bacillus cereus ATCC7064 has been overexpressed in Escherichia coli MV1184 cells under the control of the lac promoter in the genetically engineered plasmid pBCE4-2. Oligo-1,6-glucosidase was purified in large quantities and was crystallized at 25 degrees C by using a hanging drop vapor diffusion method with 53% saturated ammonium sulfate. The crystals have the shape of hexagonal bipyramids and belong to the space group P6(2) or P6(4) with lattice constants of a = b = 106.1 A, c = 120.0 A and gamma = 120 degrees.

Bacillus cereus↗