sepharose and neoagarotetraose

The oligosaccharides from agar hydrolysis have special biological activities, and exhibit application prospects in cosmetic, food and pharmaceutical industry. In this study, two novel β-agarases (AgaA and AgaB) were screened and characterized. It was found that the AgaA was an endo-type agarase which could efficiently hydrolyzed agar or agarose to form neoagarobiose (NA2), neoagarotetraose (NA4) and neoagarohexaose (NA6), while the AgaB was an exo-type and bifunctional enzyme that showed activities towards both agarose and porphyran. Based on the properties of the two enzymes, we developed modular strategy for enzymatic production of neoagarobiose through a two-stage hydrolysis reaction. The cheap substrate agar was first liquefied by AgaA at high temperature to form neoagaroligosaccharides, which together with the sulfated polysaccharides were homogenized by AgaB to form neoagarobiose as the final product. High concentration of agar (10 g/L) was almost completely converted into neoagarobiose with high purity.

Topics: Agar; Disaccharides; Galactosides; Glycoside Hydrolases; Hydrolysis; Oligosaccharides; Sepharose

An agarase gene (agaM1) was cloned, expressed and characterized by using Escherichia coli as host strain, revealing the outstanding properties of recombinant AgaM1 (rAgaM1) in agarose degradation and neoagaro-oligosaccharides (NAs) production in our previous work. In current study, agaM1 was extracellularly expressed in Bacillus subtilis, and we aim to assess the ability of the supernatant of recombinant B. subtilis fermentation broth containing rAgaM1 to degrade agarose without protein purification, which would save the cost of purification and avoid the activity loss during purification. The pH and temperature optima for the supernatant were 7.0 and 50 °C, respectively. The supernatant containing rAgaM1 has outstanding stability against 40 °C and 50 °C. Besides, we detailedly studied the possible influence factors of rAgaM1 expression in the supernatant, including pH, temperature, isopropyl β-D-thiogalactoside (IPTG) concentration, initial optical density at a wavelength of 600 nm (OD

Topics: Bacillus subtilis; Culture Media; Enzyme Stability; Galactosides; Gene Expression; Glycoside Hydrolases; Hydrogen-Ion Concentration; Isopropyl Thiogalactoside; Oligosaccharides; Recombinant Proteins; Sepharose; Temperature

Topics: Animals; Cell Line, Tumor; Cell Proliferation; Disaccharidases; Epidermal Cells; Epidermis; Galactose; Galactosides; Glycoside Hydrolases; Humans; Melanins; Melanocytes; Mice; Oligosaccharides; Rhodophyta; Seaweed; Sepharose; Skin Lightening Preparations; Skin Pigmentation; Structure-Activity Relationship

A novel β-agarase gene aga672 was cloned from strain ZC1, the typical strain of agar-degrading Aquimarina agarilytica. Gene aga672 is composed of 2130 bp, and the encoded protein Aga672 showed an amino acid sequence identity of only 42% with reported agarases. Aga672 should belong to glycoside hydrolase family 16 according to the protein sequence similarity. The molecular mass of the recombinant Aga672 was estimated to be 98 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Aga672 decomposed agarose to produce neoagarotetraose, neoagarohexaose and neoagarooctaose as the main products. That is the main difference between Aga672 and other reported agarases of family GH16. The Km and Vmax for agarose degradation were 59.8 mg mL-1 and 154.3 U mg-1, respectively. The activity of Aga672 was stable at temperatures below 40°C and at pH 7.0-11.0 with the maximal agarase activity at 25°C and pH 7.0. The results showed that agarase Aga672 could be suitable to hydrolyze the gelated agarose. Thus, it has potential applications in the production of neoagarooligosaccharides directly from red alga.

Topics: Bacterial Proteins; Cloning, Molecular; Escherichia coli; Flavobacteriaceae; Galactosides; Gene Expression; Glycoside Hydrolases; Hydrogen-Ion Concentration; Hydrolysis; Kinetics; Molecular Weight; Oligosaccharides; Recombinant Proteins; Sepharose; Substrate Specificity

An agarase gene (agaH71) was identified from Pseudoalteromonas hodoensis, an agar utilizing marine bacterium. The nucleotide sequence revealed that AgaH71 had significant homology to glycosyl hydrolase (GH) 16 agarases. agaH71 encodes a primary translation product (32.7 kDa) of 290 amino acids, including a 21-amino-acid signal peptide. The entire AgaH71 was expressed in a fused protein with glutathione-S-transferase (GST) at its N-terminal (GST-AgaH71) in Escherichia coli. Purified GST-AgaH71 had an apparent molecular weight of 59 kDa on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), which was consistent with the calculated molecular weight (58.7 kDa). Agarase activity of the purified protein was confirmed by zymogram assay. GST-AgaH71 could hydrolyze p-nitrophenyl-β-D-galactopyranoside, but not p-nitrophenyl-α-D-galactopyranoside. The optimum pH and temperature for GST-AgaH71 were 6.0 and 45 °C, respectively. GST-AgaH71 retained more than 95 and 90 % of its initial activity at 40 and 45 °C after heat treatment for 60 min, respectively. The K m and V max for agarose were 28.33 mg/ml and 88.25 U/mg, respectively. GST-AgaH71 did not require metal ions for its activity, but severe inhibition by divalent metal ions was observed. Thin-layer chromatography (TLC) analysis, mass spectrometry, and nuclear magnetic resonance (NMR) spectrometry of the GST-AgaH71 hydrolysis products revealed that GST-AgaH71 is an endo-type β-agarase that hydrolyzes agarose into predominantly neoagarotetraose and small proportions of neoagarobiose and neoagarohexaose.

Topics: Bacterial Proteins; Cloning, Molecular; Disaccharides; Escherichia coli; Galactosides; Gene Expression; Glutathione Transferase; Glycoside Hydrolases; Hydrolysis; Kinetics; Molecular Weight; Oligosaccharides; Open Reading Frames; Protein Sorting Signals; Pseudoalteromonas; Recombinant Fusion Proteins; Sepharose; Substrate Specificity

A putative agarase gene (agaH92) encoding a primary translation product (50.1 kDa) of 445 amino acids with a 19-amino-acid signal peptide and glycoside hydrolase 16 and RICIN superfamily domains was identified in an agarolytic marine bacterium, Pseudoalteromonas sp. H9 ( = KCTC23887). The heterologously expressed protein rAgaH92 in Escherichia coli had an apparent molecular weight of 51 kDa on SDS-PAGE, consistent with the calculated molecular weight. Agarase activity of rAgaH92 was confirmed by a zymogram assay. rAgaH92 hydrolyzed p-nitrophenyl-β-D-galactopyranoside, but not p-nitrophenyl-α-D-galactopyranoside. The optimum pH and temperature for rAgaH92 were 6.0 and 45°C, respectively. It was thermostable and retained more than 85% of its initial activity after heat treatment at 50°C for 1 h. rAgaH92 required Fe(2+) for agarase activity and inhibition by EDTA was compensated by Fe(2+). TLC analysis, mass spectrometry and NMR spectrometry of the GST-AgaH71 hydrolysis products revealed that rAgaH92 is an endo-type β-agarase, hydrolyzing agarose into neoagarotetraose and neoagarohexaose.

Topics: Amino Acid Sequence; Bacterial Proteins; Cloning, Molecular; Electrophoresis, Polyacrylamide Gel; Escherichia coli; Galactosides; Glycoside Hydrolases; Iron; Molecular Weight; Nitrophenylgalactosides; Oligosaccharides; Protein Sorting Signals; Pseudoalteromonas; Sepharose; Substrate Specificity

The gene agaA, of the isolated marine bacterium Pseudomonas vesicularis MA103, comprised 2958-bp nucleotides encoding a putative agarase AgaA of 985 amino acids, which was predicted to contain a signal peptide of 29 amino acids in the N-terminus, a catalytic domain of glycoside hydrolase 16 (GH16) family, a bacterial immunoglobulin group 2 (Big 2), and three carbohydrate binding modules 6 (CBM 6). The gene agaA was cloned and overexpressed in Escherichia coli, and the optimum temperatures for AgaA overexpression were 16, 20 and 24 °C. The agaA was cloned without its signal peptide for cytosolic production overexpression, whereas it was cloned with the heterologous signal peptide PelB and its endogenous signal peptide for periplasmic and extracellular productions, respectively. Extracellular and periplasmic rAgaA showed greater activity than that of cytosolic rAgaA, indicating that membrane translocation of AgaA may encourage proper protein folding. Time-course hydrolysis of agarose by rAgaA was accomplished and the products were analyzed using thin layer chromatography and matrix-assisted laser desorption inoization-time of flight mass spectrometry, indicating that AgaA from P. vesicularis was an endo-type β-1,4 agarase that cleaved agarose into neoagarotetraose and neoagarohexaose as the final products.

Topics: Bacterial Proteins; Catalytic Domain; Galactosides; Glycoside Hydrolases; Oligosaccharides; Protein Sorting Signals; Protein Transport; Pseudomonas; Sepharose

An agar-degrading bacterium, strain LGH, was isolated and identified as Cohnella sp. This strain had a capability of utilizing agar as a sole carbon source for growth and showed a strong agarolytic activity. A novel endo-type β-agarase gene agaW, encoding a primary translation product of 891 amino acids, including a 26 amino acid signal peptide, was cloned and identified from a genomic library of strain LGH. The AgaW belonged to the glycoside hydrolase (GH) GH50 family, with less than 39% amino acid sequence similarity with any known protein, and hydrolyzed agarose into neoagarotetraose as the major end product and neoagarobiose as the minor end product through other neoagarooligosaccharide intermediates, such as neoagarohexaose.

Topics: Bacillales; Carbon; Cloning, Molecular; Disaccharides; DNA, Bacterial; Galactosides; Gene Library; Glycoside Hydrolases; Hydrolysis; Molecular Sequence Data; Oligosaccharides; Sepharose; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Warfarin

AgWH50A, a novel β-agarase, was cloned from Agarivorans gilvus WH0801 by degenerate and nested PCR. It consists of 942 amino acids (105 kDa), including a 21-amino acid signal peptide. AgWH50A shares the highest amino acid sequence homology with AgaD02 from Agarivorans sp. QM38 (53%). The recombinant agarase gene was expressed in Escherichia coli and purified by affinity chromatography. Maximum enzymatic activity (Km 5.97 mg/mL and Vmax 0.781 U/mg) was observed at pH 6.0 and 30 °C. Using matrix-assisted laser desorption/ionisation-time-of-flight mass spectrometry, Fourier transform-nuclear magnetic resonance spectrometry and thin-layer chromatography, we analysed the hydrolysis products and concluded that AgWH50A is a neoagarotetraose-forming β-agarase, which can cleave agarose into neoagarotetraose. This novel agarase has potential applications in the industrial production of neoagarotetraose and provides a new agarose hydrolysis model for future research.

Topics: Alteromonadaceae; Amino Acid Sequence; Bacterial Proteins; Cloning, Molecular; Escherichia coli; Galactosides; Glycoside Hydrolases; Hydrogen-Ion Concentration; Hydrolysis; Kinetics; Molecular Sequence Data; Molecular Weight; Oligosaccharides; Open Reading Frames; Phylogeny; Protein Sorting Signals; Recombinant Proteins; Sepharose

Streptomyces coelicolor can degrade agar, the main cell wall component of red macroalgae, for growth. To constitute a crucial carbon source for bacterial growth, the alternating α-(1,3) and β-(1,4) linkages between the 3,6-anhydro-L-galactoses and D-galactoses of agar must be hydrolyzed by α/β-agarases. In S. coelicolor, DagA was confirmed to be an endo-type β-agarase that degrades agar into neoagarotetraose and neoagarohexaose. Genomic sequencing data of S. coelicolor revealed that Sco3487, annotated as a putative hydrolase, has high similarity to the glycoside hydrolase (GH) GH50 β-agarases. Sco3487 encodes a primary translation product (88.5 kDa) of 798 amino acids, including a 45-amino-acid signal peptide. The sco3487 gene was cloned and expressed under the control of the ermE promoter in Streptomyces lividans TK24. β-Agarase activity was detected in transformant culture broth using the artificial chromogenic substrate p-nitrophenyl-β-D-galactopyranoside. Mature Sco3487 (83.9 kDa) was purified 52-fold with a yield of 66% from the culture broth. The optimum pH and temperature for Sco3487 activity were 7.0 and 40°C, respectively. The K(m) and V(max) for agarose were 4.87 mg/ml (4 × 10(-5) M) and 10.75 U/mg, respectively. Sco3487 did not require metal ions for its activity, but severe inhibition by Mn(2+) and Cu(2+) was observed. Thin-layer chromatography analysis, matrix-assisted laser desorption ionization-time of flight mass spectrometry, and Fourier transform-nuclear magnetic resonance spectrometry of the Sco3487 hydrolysis products revealed that Sco3487 is both an exo- and endo-type β-agarase that degrades agarose, neoagarotetraose, and neoagarohexaose into neoagarobiose.

Topics: Agar; Bacterial Proteins; Cloning, Molecular; Disaccharides; Galactosides; Gene Expression Regulation, Bacterial; Glycoside Hydrolases; Oligosaccharides; Sepharose; Streptomyces coelicolor; Streptomyces lividans; Substrate Specificity

A β-agarase gene hz2 with 2,868 bp was cloned from the marine agarolytic bacterium Agarivorans sp. HZ105. It encoded a mature agarase HZ2 of 102,393 Da (920 amino acids). Based on the amino acid sequence similarity, agarase HZ2 was assigned to the glycoside hydrolase family 50. The β-agarase shared a gene sequence identity of 98.6% with the reported but much less characterized β-agarase agaB from Vibrio sp. JT0107. Its recombinant agarase rHZ2 was produced in E. coli cells and purified to homogeneity. The agarase rHZ2 degraded agarose and neoagarooligosaccharides with degrees of polymerization above four, to yield neoagarotetraose as the dominant product, which was different from β-agarase agaB of Vibrio sp. JT0107. The agarose hydrolysis pattern suggested that rHZ2 was an endo-type β-agarase. Beta-mercaptoethanol (90 mM) and dithiothreitol (9 mM) increased the agarase activity of rHZ2 by 72.9% and 17.3% respectively, while SDS (9 mM) inhibited the activity completely. The agarase activity was independent of Na(+), K(+), Mg(2+) and Ca(2+). The maximal enzyme activity was observed at 40°C and pH 7. The kinetic parameters K (m), V (max), K (cat), and K (cat)/K (m) values toward agarose of agarase rHZ2 were 5.9 mg ml(-1), 235 U mg(-1), 401 s(-1) and 6.8 × 10(5) M(-1) s(-1), respectively. Agarase rHZ2 could have a potential application in the production of bioactive neoagarotetraose.

Topics: Alteromonadaceae; Amino Acid Sequence; Base Sequence; Cloning, Molecular; Dithiothreitol; Enzyme Activators; Enzyme Inhibitors; Escherichia coli; Galactosides; Gene Expression; Glycoside Hydrolases; Hydrolysis; Kinetics; Mercaptoethanol; Molecular Sequence Data; Molecular Weight; Oligosaccharides; Recombinant Proteins; Sepharose; Sequence Homology, Amino Acid; Sodium Dodecyl Sulfate

Agarase genes of non-marine agarolytic bacterium Cellvibrio sp. were cloned into Escherichia coli and one of the genes obtained using HindIII was sequenced. From nucleotide and putative amino acid sequences (713 aa, molecular mass; 78,771 Da) of the gene, designated as agarase AgaA, the gene was found to have closest homology to the Saccharophagus degradans (formerly, Microbulbifer degradans) 2-40 aga86 gene, belonging to glycoside hydrolase family 86 (GH86). The putative protein appears to be a non-secreted protein because of the absence of a signal sequence. The recombinant protein was purified with anion exchange and gel filtration columns after ammonium sulfate precipitation and the molecular mass (79 kDa) determined by SDS-PAGE and subsequent enzymography agreed with the estimated value, suggesting that the enzyme is monomeric. The optimal pH and temperature for enzymatic hydrolysis of agarose were 6.5 and 42.5 degrees C, and the enzyme was stable under 40 degrees C. LC-MS and NMR analyses revealed production of a neoagarobiose and a neoagarotetraose with a small amount of a neoagarohexaose during hydrolysis of agarose, indicating that the enzyme is a beta-agarase.

Topics: Amino Acid Sequence; Bacterial Proteins; Base Sequence; Cellvibrio; Cloning, Molecular; Disaccharides; Enzyme Stability; Escherichia coli; Galactosides; Glycoside Hydrolases; Hydrogen-Ion Concentration; Hydrolysis; Molecular Sequence Data; Oligosaccharides; Recombinant Proteins; Sepharose; Temperature

To isolate and identify a versatile carbohydrate-degrading bacterium from marine environments, and characterize the extracellular agarase activity.. The I2 staining method was applied in the isolation of agarose-degrading bacteria from coastal sediments of the Jiaozhou bay nearby Qingdao city, China. The JZB09 strain was cultured in multiple media using various complex polysaccharides as the sole carbon source to test the carbohydrate utilizing abilities. The 16S rRNA gene was cloned, sequenced and analyzed to identify the taxonomic position of the strain. Crude extracellular proteins were prepared using (NH4)2SO4 precepitation method. The dialyzed enzyme extract was applied in further studies including activity testing, activity staining, and agarose degrading for oligosaccharides purifiction. Three purified oligosaccharides were individually analyzed using thin layer chromatograph (TLC) and MALDI-TOF MS method.. The agarolytic marine bacterium, Persicobacter sp. JZB09, could use multiple complex polysaccharides as the sole carbon source and grew well on agarose, cellulose and xylan. The extracellular enzyme extract exhibits efficient and extensive degradation activity on agarose with an activity of 77.2 U/mg proteins. The extracellular agarase system (EAS) in the crude extracellular enzymes contains at least two agarose depolymerases with molecular masses of approximately 45 kDa and 70 kDa, respectively. A series of degradation products from agarose by the EAS was purified and identified as neoagaro-oligosaccharides, among which neoagarotetraose was the major product of the crude enzymatic products, which suggests that beta-agarase is the major constituent of the JZB09 EAS.. The polysaccharide-degrading bacterium Persicobacter sp. JZB09 and its polysaccharide-degrading system is promising for the exploration of polysaccharide depolymerase resources including beta-agarases.

Topics: China; Cytophagaceae; Galactosides; Glycoside Hydrolases; Oligosaccharides; Sepharose; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

A bacterium with potent agar-degrading capability was isolated from the surface of a red algae, Gracilaria tenuistipitata. Based on phenotypic characteristics, 16S rDNA gene sequence and a phylogenetic analysis, this bacterium was identified and named as Flammeovirga yaeyamensis strain YT. PCR using homology-based degenerate primers was employed to clone any agarase gene belonging to GH16 family encoded in F. yaeyamensis strain YT. The resolved 1512 nucleotides revealed that the cloned gene, namely AgaYT, encodes a protein of 503 amino acids comprising a signal peptide, a glycosyl hydrolase catalytic module and a C-terminal domain with an unknown function. The recombinant protein r-AgaYT is an endo-type β-agarase hydrolyzing agarose to yield neoagarobiose and neoagarotetraose as the main hydrolytic products. The specific activity of r-AgaYT was determined about 178.6 U mg(-1) at 40°C and pH 8.0.

Topics: Amino Acid Sequence; Bacteria; Base Sequence; Cloning, Molecular; Disaccharides; Enzyme Stability; Galactosides; Glycoside Hydrolases; Humans; Molecular Sequence Data; Oligosaccharides; Phylogeny; Recombinant Proteins; Sepharose; Sequence Alignment

A gene (agrP) encoding a beta-agarase from Pseudoalteromonas sp. AG4 was cloned and expressed in Escherichia coli. The agrP primary structure consists of an 870-bp open reading frame (ORF) encoding 290 amino acids (aa). The predicted molecular mass and isoelectric point were determined at 33 kDa and 5.9, respectively. The signal peptide was predicted to be 21 aa. The deduced aa sequence showed 98.6% identity to beta-agarase from Pseudoalteromonas atlantica. The recombinant protein was purified as a fusion protein and biochemically characterized. The purified beta-agarase (AgaP) had specific activity of 204.4 and 207.5 units/mg towards agar and agarose, respectively. The enzyme showed maximum activity at 55 degrees C and pH 5.5. It was stable at pH 4.5 to 8.0 and below 55 degrees C for 1 h. The enzyme produced neoagarohexaose and neoagarotetraose from agar and in addition to that neoagarobiose from the agarose. The neoagarooligosaccharides were biologically active. Hence, AgaP is a useful enzyme source for use by cosmetic and pharmaceutical industries.

Topics: Agar; Amino Acid Sequence; Base Sequence; Disaccharides; Escherichia coli; Galactosides; Glycoside Hydrolases; Molecular Sequence Data; Oligosaccharides; Phylogeny; Pseudoalteromonas; Recombinant Proteins; Republic of Korea; Rhodophyta; Seawater; Sepharose; Sequence Alignment

A beta-agarase gene, agaB34, was functionally cloned from the genomic DNA of a marine bacterium, Agarivorans albus YKW-34. The open reading frame of agaB34 consisted of 1,362 bp encoding 453 amino acids. The deduced amino acid sequence, consisting of a typical N-terminal signal peptide followed by a catalytic domain of glycoside hydrolase family 16 (GH-16) and a carbohydrate-binding module (CBM), showed 37-86% identity to those of agarases belonging to family GH-16. The recombinant enzyme (rAgaB34) with a molecular mass of 49 kDa was produced extracellularly using Escherichia coli DH5alpha as a host. The purified rAgaB34 was a beta-agarase yielding neoagarotetraose (NA4) as the main product. It acted on neoagarohexaose to produce NA4 and neoagarobiose, but it could not further degrade NA4. The maximal activity of rAgaB34 was observed at 30 degrees and pH 7.0. It was stable over pH 5.0-9.0 and at temperatures up to 50 degrees . Its specific activity and kcat/Km value for agarose were 242 U/mg and 1.7x106/sM, respectively. The activity of rAgaB34 was not affected by metal ions commonly existing in seawater. It was resistant to chelating reagents (EDTA, EGTA), reducing reagents (DTT, beta-mercaptoethanol), and denaturing reagents (SDS and urea). The E. coli cell harboring the pUC18-derived agarase expression vector was able to efficiently excrete agarase into the culture medium. Hence, this expression system might be used to express secretory proteins.

Topics: Alteromonadaceae; Amino Acid Sequence; Base Sequence; Cloning, Molecular; Conserved Sequence; Disaccharides; Enzyme Activation; Galactosides; Glycoside Hydrolases; Hydrogen-Ion Concentration; Molecular Sequence Data; Oligosaccharides; Protein Structure, Tertiary; Recombinant Proteins; Sepharose; Sequence Homology, Amino Acid; Temperature

The beta-agarase gene agaA, cloned from a marine bacterium, Pseudoalteromonas sp. CY24, consists of 1,359 nucleotides encoding 453 amino acids in a sequence corresponding to a catalytic domain of glycosyl hydrolase family 16 (GH16) and a carbohydrate-binding module type 13 (CBM13). The recombinant enzyme is an endo-type agarase that hydrolyzes beta-1,4-linkages of agarose, yielding neoagarotetraose and neoagarohexaose as the predominant products. In two cleavage patterns, AgaA digested the smallest substrate, neoagarooctaose, into neoagarobiose, neoagarotetraose and neoagarohexaose. Site directed mutation was performed to investigate the differences between AgaA and AgaD of Vibrio sp. PO-303, identifying residues V(109)VTS(112) as playing a key role in the enzyme reaction.

Topics: Binding Sites; Catalytic Domain; Cloning, Molecular; Disaccharides; DNA, Bacterial; Galactosides; Gene Expression; Glycoside Hydrolases; Molecular Sequence Data; Mutagenesis, Site-Directed; Oligosaccharides; Protein Structure, Tertiary; Pseudoalteromonas; Sepharose; Sequence Analysis, DNA; Vibrio

An extracellular beta-agarase (AgaA34) was purified from a newly isolated marine bacterium, Agarivorans albus YKW-34 from the gut of a turban shell. AgaA34 was purified to homogeneity by ion exchange and gel filtration chromatographies with a recovery of 30% and a fold of ten. AgaA34 was composed of a single polypeptide chain with the molecular mass of 50 kDa. N-terminal amino acid sequencing revealed a sequence of ASLVTSFEEA, which exhibited a high similarity (90%) with those of agarases from glycoside hydrolase family 50. The pH and temperature optima of AgaA34 were pH 8.0 and 40 degrees C, respectively. It was stable over pH 6.0-11.0 and at temperature up to 50 degrees C. Hydrolysis of agarose by AgaA34 produced neoagarobiose (75 mol%) and neoagarotetraose (25 mol%), whose structures were identified by matrix-assisted laser desorption ionization time-of-flight mass spectroscopy and (13)C NMR. AgaA34 cleaved both neoagarohexaose and neoagarotetraose into neoagarobiose. The k (cat)/K (m) values for hydrolysis agarose and neoagarotetraose were 4.04 x 10(3) and 8.1 x 10(2) s(-1) M(-1), respectively. AgaA34 was resistant to denaturing reagents (sodium dodecyl sulfate and urea). Metal ions were not required for its activity, while reducing reagents (beta-Me and dithiothreitol, DTT) increased its activity by 30%.

Topics: Alteromonadaceae; Animals; Chromatography, Gel; Chromatography, Ion Exchange; Disaccharides; Dithiothreitol; DNA, Bacterial; Enzyme Activators; Enzyme Inhibitors; Enzyme Stability; Galactosides; Gastropoda; Glycoside Hydrolases; Hydrogen-Ion Concentration; Kinetics; Magnetic Resonance Spectroscopy; Mercaptoethanol; Molecular Sequence Data; Molecular Weight; Oligosaccharides; Sepharose; Sequence Analysis, DNA; Sequence Analysis, Protein; Sequence Homology, Amino Acid; Sodium Dodecyl Sulfate; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Temperature; Urea

Marine bacterium Vibrio sp. F-6, utilizing agarose as a carbon source to produce agarases, was isolated from seawater samples taken from Qingdao, China. Two agarases (AG-a and AG-b) were purified to a homogeneity from the cultural supernatant of Vibrio sp. F-6 through ammonium sulfate precipitation, Q-Sepharose FF chromatography, and Sephacryl S-100 gel filtration. Molecular weights of agarases were estimated to be 54.0 kDa (AG-a) and 34.5 kDa (AG-b) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The optimum pH values for AG-a and AG-b were about 7.0 and 9.0, respectively. AG-a was stable in the pH range of 4.0-9.0 and AG-b was stable in the pH range of 4.0-10.0. The optimum temperatures of AG-a and AG-b were 40 and 55 degrees C, respectively. AG-a was stable at temperature below 50 degrees C. AG-b was stable at temperature below 60 degrees C. Zn(2+), Mg(2+) or Ca(2+) increased AG-a activity, while Mn(2+), Cu(2+) or Ca(2+) increased AG-b activity. However, Ag(+), Hg(2+), Fe(3+), EDTA and SDS inhibited AG-a and AG-b activities. The main hydrolysates of agarose by AG-a were neoagarotetraose and neoagarohexaose. The main hydrolysates of agarose by AG-b were neoagarooctaose and neoagarohexaose. When the mixture of AG-a and AG-b were used, agarose was mainly degraded into neoagarobiose.

Topics: Ammonium Sulfate; Bacterial Proteins; Carbon; Cations, Divalent; Chemical Fractionation; China; Chromatography, Gel; Chromatography, Ion Exchange; Culture Media; Edetic Acid; Electrophoresis, Polyacrylamide Gel; Enzyme Activators; Enzyme Inhibitors; Enzyme Stability; Galactosides; Glycoside Hydrolases; Hydrogen-Ion Concentration; Metals; Molecular Weight; Oligosaccharides; Phylogeny; RNA, Ribosomal, 16S; Seawater; Sepharose; Sequence Analysis, DNA; Sodium Dodecyl Sulfate; Temperature; Vibrio

A marine bacterial strain that decomposes the cell walls of some seaweeds, including a Laminaria sp. and Undaria pinnatifida, has been isolated from seawater. This strain has been classified to the genus Vibrio. One of the enzymes which the bacteria secreted into the culture medium was isolated and purified 45-fold from the culture fluid by a combination of ammonium sulfate precipitation and successive rounds of anion-exchange column chromatography. Purified protein migrated as a single band (M(r), 107,000) on sodium dodecyl sulfate-polyacrylamide gels. By amino acid sequence analysis, it was determined that this protein had a single N-terminal sequence that did not exhibit identity with the sequences of other agarases from marine bacteria. This novel enzyme was found to be an endo-type beta-agarase (EC 3.2.1.81) which hydrolyzes the beta-1,4 linkage of agarose to yield neoagarotetraose [O-3,6-anhydro-alpha-L-galactopyranosyl (1-->3)-O-beta-D-galactopyranosyl(1-->4)-O-3,6-anhydro-alpha-L-galactopy ranosyl (1-->3)-D-galactose] and neoagarobiose [O-3,6-anhydro-alpha-L-galactopyranosyl (1-->3)-D-galactose] at a pH of around 8. The optimum temperature was 30 degrees C. This enzyme did not decompose sodium alginate or lambda-, iota-, or kappa-carrageenan. This enzyme may be of practical application in gene technology in the isolation of DNA fragments from agarose gels after electrophoresis.

Topics: Amino Acid Sequence; Amino Acids; Carbohydrate Sequence; Disaccharides; DNA; Galactosides; Glycoside Hydrolases; Hydrogen-Ion Concentration; Kinetics; Molecular Sequence Data; Oligosaccharides; Seawater; Sepharose; Substrate Specificity; Temperature; Vibrio; Water Microbiology