Attachment Of Chemical Groups Research Articles

Removal of Atrazine from contaminated water by functionalized graphene quantum dots

The limitation of clean water supplies and the increment of water pollution resources, like industrial processes, oil pollution, and herbicides, are urgent reasons for introducing new techniques for treating contaminated water. Atrazine is heavily used as a herbicide due to its high effectiveness and low price. However, its environmental persistence causes water contamination, and human exposure to Atrazine is linked to several health effects. This work presents a simulation study of the possibility of removing the Atrazine from water by functionally activated graphene quantum dots (GQDs), using density functional theory (DFT) at B3LYP/3-21G level. The activity of GQDs C46 with a total dipole moment of 0.9 is enhanced by the attachment of chemical groups; for instance, attaching CN and NO2 groups increases the total dipole moment to 8.744 and 9.123, respectively. The effect of the functionalized groups Carboxyl and cyanide was investigated, and confirmed that there was no structure deformation due to the functionalization process. Analysis of the obtained data shows the remarkable adsorption ability of GQDs activated by CN and NO2 groups toward the removal of atrazine herbicides due to positive adsorption energy 1.31, 128, and 1.3 eV obtained from pristine, carboxyl graphene, and cyanide graphene respectively. According to the calculated total charge on the complexes Atrazine and GQDs and Functionalized GQD, charge transfer mainly depends on the interaction pattern. The values of charges were − 0.02, 0.004, and − 0.004 for pristine, carboxyl, and cyanide graphene, respectively. Therefore, the observed results demonstrated the possibility of applying the chemically modified carbon quantum dots as a potential candidate for the treatment of contaminated water.

Fluorescent analogues of BeKm-1 with high and specific activity against the hERG channel.

Peptidic toxins that target specifically mammalian channels and receptors can be found in the venom of animals. These toxins are rarely used directly as tools for biochemical experiments, and need to be modified via the attachment of chemical groups (e.g., radioactive or fluorescent moieties). Ideally, such modifications should maintain the toxin specificity and affinity for its target. With the goal of obtaining fluorescent derivatives of BeKm-1, a toxin from the scorpion species Buthus eupeus that selectively inhibits the voltage-gated potassium ion channel hERG, we produced four active analogues using a model of BeKm-1 docking to the outer mouth of the channel. In these BeKm-1 analogues, the natural peptide was linked to the fluorescent cyanine 5 (Cy5) probe via four different linkers at Arg1 or Arg/Lys27. All analogues retained their specificity towards the hERG channel in electrophysiological experiments but displayed a lesser affinity. These results validate our strategy for designing toxin analogues and demonstrate that different chemical groups can be attached to different residues of BeKm-1.

Covalent Modification of Bacteriophage T4 DNA Inhibits CRISPR-Cas9.

ABSTRACTThe genomic DNAs of tailed bacteriophages are commonly modified by the attachment of chemical groups. Some forms of DNA modification are known to protect phage DNA from cleavage by restriction enzymes, but others are of unknown function. Recently, the CRISPR-Cas nuclease complexes were shown to mediate bacterial adaptive immunity by RNA-guided target recognition, raising the question of whether phage DNA modifications may also block attack by CRISPR-Cas9. We investigated phage T4 as a model system, where cytosine is replaced with glucosyl-hydroxymethylcytosine (glc-HMC). We first quantified the extent and distribution of covalent modifications in T4 DNA by single-molecule DNA sequencing and enzymatic probing. We then designed CRISPR spacer sequences targeting T4 and found that wild-type T4 containing glc-HMC was insensitive to attack by CRISPR-Cas9 but mutants with unmodified cytosine were sensitive. Phage with HMC showed only intermediate sensitivity. While this work was in progress, another group reported examples of heavily engineered CRISRP-Cas9 complexes that could, in fact, overcome the effects of T4 DNA modification, indicating that modifications can inhibit but do not always fully block attack.