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A classic example of NGP is the reaction of a sulfur or nitrogen mustard with a nucleophile, the rate of reaction is much higher for the sulfur mustard and a nucleophile than it would be for a primary or secondary alkyl chloride without a heteroatom. [4] Ph−S−CH 2 −CH 2 −Cl reacts with water 600 times faster than CH 3 −CH 2 −CH 2 ...
A hydroxide ion acting as a nucleophile in an S N 2 reaction, converting a haloalkane into an alcohol. In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they ...
For example, OH − is a better nucleophile than water, and I − is a better nucleophile than Br − (in polar protic solvents). In a polar aprotic solvent, nucleophilicity increases up a column of the periodic table as there is no hydrogen bonding between the solvent and nucleophile; in this case nucleophilicity mirrors basicity.
A sulfur nucleophile improved the enzymes transferase activity (sometimes called subtiligase). Selenium and tellurium nucleophiles converted the enzyme into an oxidoreductase. [51] [52] When the nucleophile of TEV protease was converted from cysteine to serine, it protease activity was strongly reduced, but was able to be restored by directed ...
The carbonyl center in thioesters is more reactive toward amine than oxygen nucleophiles, giving amides: Thioesters are components of the native chemical ligation method for peptide synthesis. This reaction is exploited in native chemical ligation, a protocol for peptide synthesis. [8] In a related reaction, thioesters can be converted into ...
Sulfur is metabolized by all organisms, from bacteria and archaea to plants and animals. Sulfur can have an oxidation state from -2 to +6 and is reduced or oxidized by a diverse range of organisms. [1] The element is present in proteins, sulfate esters of polysaccharides, steroids, phenols, and sulfur-containing coenzymes. [2]
This is because α-nucleophiles showing the α-effect have smaller HOMO(nucleophile)-LUMO(substrate) gap, in other words, high HOMO energy level that allows more orbital interaction. Examples of α-nucleophiles with α-effects are shown in Figure 4. The α-nucleophiles have smaller HOMO lobes than the parent normal nucleophile. Figure 4.
Radioactive sulfur-35 was used to label the protein sections of the T2 phage, because sulfur is contained in protein but not DNA. [6] Hershey and Chase inserted the radioactive elements in the bacteriophages by adding the isotopes to separate media within which bacteria were allowed to grow for 4 hours before bacteriophage introduction.