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The thiourea hydrogen bonds to the nitro group and stabilizes the incoming negative charge, while the amine acts a specific base to activate the nucleophile. This is an example of bifunctional catalysis. Hydrogen-bond catalysis is a type of organocatalysis that relies on use of hydrogen bonding interactions to accelerate and control organic ...
Thioureas are often found to be stronger hydrogen-bond donors (i.e., more acidic) than ureas [7] because their amino groups are more positively charged. Quantum chemical analyses revealed that this counterintuitive phenomenon, which is not explainable by the relative electronegativities of O and S, results from the effective steric size of the ...
Carbonic anhydrase was initially isolated and characterised from red blood cells in 1933, with simultaneous reports by Meldrum and Roughton (at Cambridge University in the United Kingdom) and by Stadie and O’Brien (at the University of Pennsylvania in the United States), [7] [8] both while searching for a "catalytic factor... necessary for rapid transit of the HCO 3-[bicarbonate anion] from ...
Researchers have since conducted increasingly detailed investigations of the triad's exact catalytic mechanism. Of particular contention in the 1990s and 2000s was whether low-barrier hydrogen bonding contributed to catalysis, [18] [19] [20] or whether ordinary hydrogen bonding is sufficient to explain the mechanism.
A hydrogen bonds to one of the nitrogen atoms, breaking its bond with carbon, and releasing an NH 3 molecule. Simultaneously, the bond between the oxygen and the 6-coordinate nickel is broken. This leaves a carbamate ion coordinated to the 5-coordinate Ni, which is then displaced by a water molecule, regenerating the enzyme.
A recently announced class action lawsuit filed against T-Mobile alleges the company has disguised a hidden fee as a government charge for two decades.. The wireless network allegedly ...
Hydrogen bond: A hydrogen bond is a specific type of dipole-dipole interaction between a partially positive hydrogen atom and a partially negative electron donor that contain a pair of electrons such as oxygen, fluorine and nitrogen. The strength of hydrogen bond depends on the chemical nature and geometric arrangement of each group.
Anthony Richardson scored on a 2-point conversion run up the middle with 12 seconds remaining in the fourth quarter to give the Indianapolis Colts a 25–24 win over the New England Patriots on ...