ABSTRACT
Palmatine, an isoquinoline alkaloid, is an important medicinal herbal extract with diverse pharmacological and biological properties. In this work, spectroscopic and molecular modeling approaches were employed to reveal the interaction between palmatine and DNA isolated from herring sperm. The absorption spectra and iodide quenching results indicated that groove binding was the main binding mode of palmatine to DNA. Fluorescence studies indicated that the binding constant (K) of palmatine and DNA was ~ 10(4)L·mol(-1). The associated thermodynamic parameters, ΔG, ΔH, and ΔS, indicated that hydrogen bonds and van der Waals forces played major roles in the interaction. The effects of chemical denaturant, thermal denaturation and pH on the interaction were investigated and provided further support for the groove binding mode. In addition to experimental approaches, molecular modeling was conducted to verify binding pattern of palmatine-DNA.
Subject(s)
Berberine Alkaloids/chemistry , DNA/chemistry , Animals , Binding Sites , Circular Dichroism , Fishes , Hydrogen Bonding , Kinetics , Male , Models, Molecular , Spectrometry, Fluorescence , Spermatozoa/chemistry , ThermodynamicsABSTRACT
An alkaline active xylanase, XynBYG, was purified from an alkaliphilic Bacillus pumilus BYG, which was newly isolated from paper mill effluent. It had an optimum pH of 8.0-9.0, and showed good stability after incubated at pH 9.0 for 120 min. The optimum temperature for the activity was 50°C, and the enzyme retained below 55% of its original activity for 30 min at 55°C. The gene coding for XynBYG consists of 687 bp and encodes 229 amino acids. Similarity analysis indicated that XynBYG belong to family 11 glycosyl hydrolases. Site-directed mutagenesis was performed to replace five sites (Tyr/Ser) to Arg/Glu and the results demonstrated that the optimum temperature of the mutant Y7 (S39R-T146E) increased 5°C and the half-life of inactivation (T1/2) at 60 and 65°C was 1 h and 25 min, respectively. Thus, it provides a potential xylanase that can meet the harsh conditions in the industrial applications.
Subject(s)
Alkalies/pharmacology , Bacillus/enzymology , Bacillus/isolation & purification , Endo-1,4-beta Xylanases/biosynthesis , Industrial Waste/analysis , Paper , Waste Disposal, Fluid , Adaptation, Physiological/drug effects , Bacillus/genetics , Cloning, Molecular , Electrophoresis, Polyacrylamide Gel , Enzyme Stability/drug effects , Escherichia coli/drug effects , Escherichia coli/metabolism , Gene Expression Regulation, Bacterial/drug effects , Genes, Bacterial/genetics , Hydrogen-Ion Concentration/drug effects , Mutagenesis, Site-Directed , Sequence Analysis, DNA , TemperatureABSTRACT
Here, we present the electroporation as a feasible and efficient method for introducing circularized and linearized DNA into Bacillus subtilis chromosome. Two integration experiments were carried out and demonstrated the feasibility and efficiency of electroporation to introduce the target DNA into the B. subtilis chromosome. By using of electroporation, a multiple-cistron contained five genes from B. subtilis biotin biosynthetic pathway was introduced into the B. subtilis chromosome efficiently and created a repeated copy in chromosome via a single crossover event. Then an ectopic promoter was introduced conveniently into the upstream of one of the repeated multiple-cistron via a double crossover event. To further demonstrate the application of electroporation in genetic research, the early sporulation gene spo0A of B. subtilis was knocked out and, consequently, the null of sporulation and logged growth was observed in this study. Thus, the electroporation as an alternative method of integration in B. subtilis is feasible and practical.
