To enhance the thermostability and storage stability of alpha-cyclodextrin glycosyltransferase (a-CGTase), we added specific chemical additives into the preparation of alpha-CGTase, and studied the effect of additives on the storage stability of alpha-CGTase at different temperatures. Then we measured the protein structure of CGTase in the far UV (200-250 nm) and near UV (250-320 nm) ranges respectively by Circular dichroism (CD) spectra under high temperature and analyzed the relationship between thermostability and protein structure. The results indicated that the addition of selected additives (gelatin, glycerin, CaCl2 and PEG400) enhanced the thermostability of alpha-CGTase dramatically. After 45 days, the preparation of alpha-CGTase still had 100% of the enzyme activity with different additives superimposed at the optimum concentration at 40 degrees C. The CD spectra of alpha-CGTase showed that glycerin could protect the secondary and the tertiary structure of the CGTase under high temperature and therefore the enzyme maintained its high activity. Chemical additives can improve the stability of alpha-CGTase significantly and they preserve the enzyme activity by protecting its secondary structure.
Enzyme Stability ; drug effects ; Escherichia coli ; genetics ; metabolism ; Glucosyltransferases ; biosynthesis ; chemistry ; genetics ; Glycerol ; chemistry ; Paenibacillus ; enzymology ; Recombinant Proteins ; biosynthesis ; chemistry ; genetics

NDM-1 (New Delhi metallo-beta-lactamase) gene encodes a metallo-beta-lactamase (MBL) with high carbapenemase activity, which makes the host bacterial strain easily dispatch the last-resort antibiotics known as carbapenems and cause global concern. Here we present the bioinformatics data showing an unexpected similarity between NDM-1 and beta-lactamase II from Erythrobacter litoralis, a marine microbial isolate. We have further expressed these two mature proteins in E. coli cells, both of which present as a monomer with a molecular mass of 25 kDa. Antimicrobial susceptibility assay reveals that they share similar substrate specificities and are sensitive to aztreonam and tigecycline. The conformational change accompanied with the zinc binding visualized by nuclear magnetic resonance, Zn(2+)-bound NDM-1, adopts at least some stable tertiary structure in contrast to the metal-free protein. Our work implies a close evolutionary relationship between antibiotic resistance genes in environmental reservoir and in the clinic, challenging the antimicrobial resistance monitoring.
Amino Acid Sequence ; Anti-Bacterial Agents ; pharmacology ; Aztreonam ; pharmacology ; Cephalosporinase ; chemistry ; genetics ; metabolism ; Computational Biology ; methods ; Drug Resistance, Bacterial ; genetics ; Enzyme Stability ; drug effects ; Evolution, Molecular ; Minocycline ; analogs & derivatives ; pharmacology ; Molecular Sequence Data ; Phylogeny ; Protein Structure, Tertiary ; drug effects ; Sequence Homology, Nucleic Acid ; Sphingomonadaceae ; drug effects ; enzymology ; genetics ; Tigecycline ; Zinc ; pharmacology ; beta-Lactamases ; chemistry ; genetics ; metabolism

Angiogenesis is critical and indispensable for tumor progression. Since VEGF is known to play a central role in angiogenesis, the disruption of VEGF-VEGF receptor system is a promising target for anti-cancer therapy. Previously, we reported that a hexapeptide (RRKRRR, RK6) blocked the growth and metastasis of tumor by inhibiting VEGF binding to its receptors. In addition, dRK6, the D-form derivative of RK6, retained its biological activity with improved serum stability. In the present study, we developed a serum-stable branched dimeric peptide (MAP2-dRK6) with enhanced anti-VEGF and anti-tumor activity. MAP2-dRK6 is more effective than dRK6 in many respects: inhibition of VEGF binding to its receptors, VEGF- and tumor conditioned medium-induced proliferation and ERK signaling of endothelial cells, and VEGF-induced migration and tube formation of endothelial cells. Moreover, MAP2-dRK6 blocks in vivo growth of VEGF-secreting colorectal cancer cells by the suppression of angiogenesis and the subsequent induction of tumor cell apoptosis. Our observations suggest that MAP2-dRK6 can be a prospective therapeutic molecule or lead compound for the development of drugs for various VEGF-related angiogenic diseases.
Amino Acid Sequence ; Angiogenesis Inhibitors/*pharmacology ; Animals ; Cell Movement/drug effects ; Cell Proliferation/drug effects ; Colorectal Neoplasms/*pathology/secretion ; Endothelial Cells/cytology/drug effects/enzymology ; Enzyme Activation/drug effects ; Extracellular Signal-Regulated MAP Kinases/metabolism ; Humans ; Mice ; Mice, Nude ; Molecular Sequence Data ; Neovascularization, Pathologic/pathology/prevention & control ; Neovascularization, Physiologic/drug effects ; Peptides/chemistry/*pharmacology ; Protein Multimerization/*drug effects ; Protein Stability/drug effects ; Rats ; Serum ; Vascular Endothelial Growth Factor A/*antagonists & inhibitors/secretion

The lipase labeled with the fluorescein isothiocyanat (FITC) was immobilized on the derivatives of the polyethylene glycol. The article discussed the effect of factors on the characters of lipase and analyzed the relationships among the activity of lipase, conformation, and fluorescence spectrum while the activity and the fluorescence spectrum of immobilized lipase were determined. The results demonstrated that polyethylene glycol 400-diacrylate could form appropriate network to improve the activity of enzyme. Adding ligand induced the lipase's catalytic conformation to increase the activity twice more than before. The active centre of lipase could be released by the extraction of ligand thus increasing the activity. After immobilization, the stability of labeled lipase improved greatly: immobilized lipases retained more than 70% and 60% of initial activity under conditions of 90 degrees C and strong acid or alkali, respectively. After immersing immobilized lipases into guanidine hydrochloride or urea for 15 days, the lipases retained upwards of 70% activity. The fluorescence spectrum could obviously reflect the changes of the activity and conformation of lipase. The fluorescence intensity was the minimum in the optimal pH and temperature. In the denaturing agent it declined as time passed. These results indicated that the unfolded processes of immobilized lipases are different under different conditions.
Dextrans ; chemistry ; Enzyme Stability ; Enzymes, Immobilized ; chemistry ; metabolism ; Fluorescein-5-isothiocyanate ; analogs & derivatives ; chemistry ; Fluorescent Dyes ; chemistry ; Lipase ; chemistry ; metabolism ; Polyethylene Glycols ; chemistry ; Protein Unfolding ; drug effects

LysinB (LysB) in mycobacteriophage D29 was cloned and expressed and its enzymatic properties were analysed. The lysB gene was amplified by PCR from mycobacteriophage D29 genomic DNA and inserted into pET22b vector. The constructed recombinant plasmid was transformed into Escherichia coli BL21(DE3) to express fusion protein, which was purified by Ni-NTA column and enzymatic activity detected. The results showed that expression plasmid pET22b-lysB was constructed successfully. Highly purified recombination protein (His-LysB) was obtained 33.2 mg from 1 L LB culture medium. A screening for His-LysB activity on esterase and lipase substrates confirmed the lipolytic activity. With p-nitrophenyl butyrate as substrate, the thermal stability of the enzyme was poor when the temperature was above 30 degrees C. The enzyme exhibited higher stability at pH 5.0-9.5. The optimum temperature and pH for the lipolytic activity of His-LysB were 23 degrees C and 7.5 respectively. Under the optimum conditions, the specific activity of His-LysB was 1.3 U/mg. Zn2+, CU2+, Mg2+, Mn2+ and phenylmethane sulfonyl fruoride severely inhibited the lipolytic activity of His-LysB. The result provides a new option for tuberculosis drug research and development.
Cloning, Molecular ; Enzyme Stability ; Escherichia coli ; genetics ; metabolism ; Mycobacteriophages ; enzymology ; Mycobacterium tuberculosis ; drug effects ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; isolation & purification ; metabolism ; Viral Proteins ; biosynthesis ; genetics

Keeping an enzyme in its native form with high catalytic activity is of great significance. In the present study, thermal stabilizers of horseradish peroxidase (HRP) were screened. The results indicated that thermal stability of HRP was enhanced by magnesium sulphate and gelatin. A synergic effect of magnesium sulphate and gelatin was observed. In the presence of the stabilizer, the enzymatic activity of HRP remained 89% after kept for 80 h at 50 degrees C and 57% for 90 days at room temperature. Thermal alterations of HRP structure in the absence and presence of the stabilizers were explored by using UV absorption spectra at 402 nm (Soret band), intrinsic fluorescence and 8-anilinonaphthalene-1-sulfonic acid (ANS) fluorescence. The results suggested that magnesium sulphate and gelatin attenuated the extent of unfolding of HRP and therefore the native enzyme structure was stabilized.
Drug Synergism ; Enzyme Stability ; drug effects ; Gelatin ; pharmacology ; Horseradish Peroxidase ; metabolism ; Hot Temperature ; Magnesium Sulfate ; pharmacology

We immobilized Candida sp. lipase onto seven kinds of industrial adsorption and ion exchange resins. By determining the activity of each immobilized enzyme, the weakly basic anionic exchange resin of D301 showed the best results for the immobilization of Candida sp. lipase. Comparing the scanning electron micrographs of D301 with Novozym 435 (immobilized Candida antarctica lipase B from Novo Nordisk Corp.), we selected D301 as a carrier for the immobilization of Candida sp. lipase. And we pretreated the resin D301 with the bifunctional agent glutaraldehyde and crosslinked it with Candida sp. lipase. The optimal conditions for the immobilization of Candida sp. lipase were as follows: 8 mL of the amount of 5% glutaraldehyde solution, five hours of the time pretreated D301 with glutaraldehyde, 1.0 g/L the concentration of Candida sp. lipase used, pH of the phosphate buffered, 6.0 and 10 hours of time for immobilization, respectively. The activity of immobilized enzyme was over 35 U/mg and the efficiency of immobilization was around 3.5 Ul(mg x h).
Candida ; enzymology ; Enzyme Stability ; Enzymes, Immobilized ; chemistry ; drug effects ; metabolism ; Ion Exchange Resins ; pharmacology ; Lipase ; chemistry ; metabolism

To obtain thermostable aspartate aminotransferase, the gene aspC from an extremely thermophilic bacterium, Thermus thermophilus HB8 was cloned, and its product was overexpressed in Escherichia coli BL21 (DE3) and Rosetta (DE3). The expression in Rosetta (DP3) was more efficient. The optimum reactive pH was 7, and the recombinant enzyme activity changed little when incubated in the buffer of pH8 - 10 on 37 degrees C for 1 h. The optimum reactive temprature was 75 degrees C, and the recombinant enzyme was more stable on the temperature of 25 - 55 degrees C. The half life of recombinant enzyme on 65 degrees C was 3.5 h, on 75 degrees C was 2.5 h. KmKG was 7.559 mmol/L, VmaxKG was 0.086 mmol/(L x min), KmAsp was 2.031 mmol/L, VmaxAsp was 0.024 mmol/(L x min). Ca2+, Fe3+, Mn2+ inhibited enzyme activity softly.
Aspartate Aminotransferases ; genetics ; isolation & purification ; metabolism ; Bacterial Proteins ; genetics ; isolation & purification ; metabolism ; Biocatalysis ; drug effects ; Electrophoresis, Polyacrylamide Gel ; Enzyme Stability ; drug effects ; Escherichia coli ; genetics ; Gene Expression Regulation, Bacterial ; Gene Expression Regulation, Enzymologic ; Hydrogen-Ion Concentration ; Kinetics ; Metals ; pharmacology ; Recombinant Proteins ; isolation & purification ; metabolism ; Temperature ; Thermus thermophilus ; enzymology ; genetics

The purification and the characteristics of an enzyme from Morganella morganii J-8, which could produce d-pseudoephedrine from 1-phenyl-2-methylamine-acetone, were performed in this study. In this research, first, cells were disrupted by ultrasonic treatment at 4 degrees C. The carbonyl enantioselective reductase was purified with a combination of ammonium precipitation, Phenyl Superose hydrophobic chromatography, DEAE anion exchange, and native polyacrylamide gel electrophoresis. The molecular mass of the purified enzyme subunit was estimated to be 42.5kD on sodium dodecyl sulfate-polyacrylamide electrophoresis (SDS-PAGE). The native molecular mass of the enzyme that was analyzed by high-performance liquid chromatography was found out to be 84.1 kD, which indicated that the enzyme was a dimmer. The purified enzyme was analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and the result showed that the purified enzyme had high homology with leucine dehydrogenase.
Bacterial Proteins ; chemistry ; isolation & purification ; metabolism ; Biocatalysis ; drug effects ; Chromatography, High Pressure Liquid ; Electrophoresis, Polyacrylamide Gel ; Enzyme Stability ; drug effects ; Hydrogen-Ion Concentration ; Kinetics ; Leucine Dehydrogenase ; metabolism ; Metals, Heavy ; pharmacology ; Molecular Weight ; Morganella morganii ; enzymology ; metabolism ; Oxidoreductases ; chemistry ; isolation & purification ; metabolism ; Pseudoephedrine ; chemistry ; metabolism ; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ; Stereoisomerism ; Temperature

OBJECTIVETo investigate the effect of 2-phenoxyethanol on potency of Sabin inactivated poliomyelitis vaccine (IPV).

METHODSSabin IPV samples containing 5 mg or 7 mg 2-phenoxyethanol each dosage respectively were placed separately at 4 degrees C, 37 degrees C for 2 days and 7 days. D-antigen contents were tested with ELISA method. Then neutralizing antibodies in mice and guinea pigs were detected. The safety experiment was performed according to unusual toxicity test of China requirement for biological product.

RESULTSAfter addition of 2-phenoxyethanol, the I, II, and III D-antigen contents of Sabin IPV did not change. The antibody levels in mice and guinea pigs were not different between experimental group and control group. Animals were safe during observation period.

CONCLUSION2-Phenoxyethanol had no effect on potency and safety of Sabin IPV. It can be used as antiseptic for Sabin IPV.

Animals ; Anti-Infective Agents, Local ; administration & dosage ; pharmacology ; toxicity ; Antigens, Viral ; analysis ; immunology ; Body Weight ; drug effects ; Cercopithecus aethiops ; Drug Stability ; Enzyme-Linked Immunosorbent Assay ; Ethylene Glycols ; administration & dosage ; pharmacology ; toxicity ; Guinea Pigs ; Mice ; Neutralization Tests ; Poliovirus Vaccine, Inactivated ; administration & dosage ; immunology ; toxicity ; Vero Cells