Inhibition of Pore Formation by Blocking the Assembly of Staphylococcus aureus α-Hemolysin Through a Novel Peptide Inhibitor: an In Silco Approach

Staphylococcus aureus self-assembling α-hemolysin heptamer is an acute virulence factor that determines the severity of S. aureus infections. Hence, inhibiting the heptamer formation is of considerable interest. However, both natural and chemical inhibitors reported so far has difficulties related to toxicity, bioavailability, and solubility, which necessitate in identifying some alternatives. Hence, in this study, potential peptides for α-hemolysin inhibition was developed using in silico based approach. Haddock server was used to understand the residues involved in complex formation. Based on the key residues involved in the interaction, 20 peptides were designed and docked with the α-hemolysin monomer (Chain A). Further, the best scored Chain A-peptide complex was chosen and docked with Chain B to identify the ability of dimer formation in the presence of designed peptide. The stability of the Chain A–B dimer, Chain A-peptide and Chain A-peptide-Chain B complex was studied by performing molecular dynamic simulation over 3,000 ps. The peptide IYGSKANRQTDK was found to be binding efficiently with Chain A of α-hemolysin with highest binding energy and also revealed that the designed peptide disturbed the dimer formation, which provided useful information in developing promising lead for inhibiting α-hemolysin assembly in the future.     

An efficient synthesis of 3′-O-triazole modified guanosine-5′-O-monophosphate using click chemistry

First chemical synthesis of 3′-O-1,2,3-triazolyl-guanosine-5′-O-monophosphate by copper catalyzed click chemistry is described. The present cycloaddition reaction involves, in situ generation of azide from the corresponding bromide followed by copper catalyst cycloaddition with 3′-O-propargyl guanosine monophosphate in water, in the presence of catalytic amount of β-cyclodextrin. The CuAAC reaction is highly regioselective forming 1,4-cycloadduct with good yield and high purity. The final compound, 3′-O -triazole substituted guanosine monophosphate has the potential to use in various biomolecules such as labeled nucleic acids, mRNA dinucleotide cap analogs for molecular biology and their applications in the therapeutic field.     

Crystalline fructose 1,6-bisposphatase from chicken breast muscle.

Fructose 1,6-bisphosphatase has been isolated and crystallized in high yield from chicken breast muscle, which is a rich source of this enzyme. The specific activity assayed at pH 7.4 and 25 °C in the presence of 0.2 mm MnCl₂ 0.1 mm EDTA, and 40 mm ammonium sulfate is 50–60 units/mg, making this one of the most active fructose bisphosphatases yet described. The K_m for fructose bisphosphate is 8.3 μm. AMP (0.4 μm) inhibits the activity at pH 7.4 almost completely. EDTA can be replaced as activator by citrate or histidine, which both give maximum activation at millimolar concentrations. Citrate is as effective as EDTA. The enzyme has a molecular weight of 144,000 and is composed of four subunits having a molecular weight of 36,000. Amino- and carboxy-terminal analyses indicate that the subunits are identical.     

A novel thermostable and halostable carboxymethylcellulase from marine bacterium <Emphasis Type="Italic">Bacillus licheniformis</Emphasis>AU01

A novel thermostable, halostable carboxymethylcellulase (CMCase) from a marine bacterium Bacillus licheniformisAU01 was purified 10.4-fold with 18% yield with a specific activity of 88.43 U/mg and the molecular weight was estimated as 37 kDa. The enzyme was optimally active at pH 9–10 and temperature 50–60°C and it was most stable up to pH 12 and 20–30% of NaCl concentration. The enzyme activity was reduced when treated with Hg²⁺, Fe²⁺ and EDTA and stimulated by Co²⁺, Mn²⁺, Mg²⁺ and Ca²⁺. Various cationic, anionic detergents and commercial detergents were not much affected CMCase activity.     

Impact of zinc,selenium and lycopene on capsaicin induced mutagenicity and oxidative damage in mice

Capsaicin is employed as a condiment and colorant in the cosmetic and pharmaceutical industries. Metabolism of capsaicin produces reactive phenoxy radicals, which inflict damage to DNA. Micronutrients such as zinc and selenium facilitate the expression of tissue repair factors, and lycopene has natural antioxidant action. The current study investigated the possible protective role of zinc, selenium and lycopene singly and in combination in ameliorating capsaicin induced mutagenicity. Fifty four Swiss albino mice received the vehicle, zinc (10 mg/kg), selenium (2 mg/kg), lycopene (2 mg/kg) alone, capsaicin alone (2 mg/kg), and capsaicin along with zinc (10 mg/kg), selenium (2 mg/kg) and lycopene (2 mg/kg) in combination by the oral route for 32 days. Animals were killed 24 h after the last treatment, and micronuclei formation in bone marrow and peripheral blood were assessed. Antioxidant status in plasma, the total protein, nucleic acids, and DNA fragmentation was assessed in the liver homogenate. Capsaicin substantially damaged nuclear material and increased oxidative stress. Individual therapy with lycopene was most effective in reducing micronuclei formation, lipid peroxidation, and in augmenting ferric reducing ability of plasma. This was closely followed by zinc and selenium. Zinc protected against DNA fragmentation followed by lycopene and selenium. The combination therapy was effective over individual treatment against DNA fragmentation, micronuclei and malondialdehyde formation. The combination did not exert a substantial benefit over individual therapy in enhancing the total antioxidant ability of plasma. The risk of capsaicin induced mutagenicity was lowered with the combination by reducing the generation of free radicals and by enhancing tissue repair.     

Bacterial compounds,as biocontrol agent against early blight (Alternaria solani) and tobacco cut worm (Spodoptera litura Fab.) of tomato (Lycopersicon esculentum Mill.)

Abstract

Tomato, the important vegetable crop faces yield loses by foliar disease, Early Blight caused by Alternaria solani and infestation by tobacco cut worm, Spodoptera litura. Synthetic pesticides used for disease and pest control resulted in environmental pollution as well as development of resistance. By way of a need to develop a new biopesticide, bacteria were tested for their anti-fungal and insecticidal activity. Volatile compounds and peptides from the bacteria, Bacillus subtilis, Staphylococcus aureus and Pseudomonas aeruginosa were able to inhibit the hyphal growth and melanin production of A. solani. S. aureus showed the highest inhibitory effect as well as reduced the disease severity. B. subtilis exhibited the highest mortality rate of 87% and 83% against I and II instar of S. litura, respectively. The bacteria offered effective biocontrol at 35?°C. Bioactive substances from the bacteria can be used as potential biocontrol agents against the pest and disease of tomato.