Sandbox Reserved 468: Difference between revisions
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== Mechanism of Action == | == Mechanism of Action == | ||
There is not a generally accepted mechanism of action for this enzyme but there are three possible catalytic mechanisms published. | There is not a generally accepted mechanism of action for this enzyme but there are three possible catalytic mechanisms published. Note that all of these mechanisms somehow involve the zinc ion, which is found in the catalytic domain and believed to play an important role in catalysis. | ||
In the first mechanism, Browner M.F. and colleagues proposed the base-catalysis mechanism, carried out by the conserved glutamate residue and the Zn2+ ion. | In the first mechanism, Browner M.F. and colleagues proposed the base-catalysis mechanism, carried out by the conserved glutamate residue and the Zn2+ ion [5][6]. | ||
In the second mechanism, the Matthews-mechanism, Kester and Matthews suggested an interaction between a water molecule and the Zn2+ ion during the acid-base catalysis. | In the second mechanism, the Matthews-mechanism, Kester and Matthews suggested an interaction between a water molecule and the Zn2+ ion during the acid-base catalysis [5][6]. | ||
In the third mechanism, the Manzetti-mechanism, Manzetti Sergio and colleagues provided evidence that a coordination between water and zinc during catalysis was unlikely, and suggested a third mechanism wherein a histidine participates in catalysis by allowing the Zn2+ ion to assume a quasi-penta coordinated state, via its dissociation from it. In this state, the Zn2+ ion is coordinated with the two oxygen atoms from the catalytic glutamic acid, the substrate's carbonyl oxygen atom, and the two histidine residues, and can polarize the glutamic acid's oxygen atom, proximate the scissile bond, and induce it to act as reversible electron donor. This forms an oxyanion transition state. At this stage, a water molecule acts on the dissociated scissile bond and completes the hydrolyzation of the substrate [5][6]. | In the third mechanism, the Manzetti-mechanism, Manzetti Sergio and colleagues provided evidence that a coordination between water and zinc during catalysis was unlikely, and suggested a third mechanism wherein a histidine participates in catalysis by allowing the Zn2+ ion to assume a quasi-penta coordinated state, via its dissociation from it. In this state, the Zn2+ ion is coordinated with the two oxygen atoms from the catalytic glutamic acid, the substrate's carbonyl oxygen atom, and the two histidine residues, and can polarize the glutamic acid's oxygen atom, proximate the scissile bond, and induce it to act as reversible electron donor. This forms an oxyanion transition state. At this stage, a water molecule acts on the dissociated scissile bond and completes the hydrolyzation of the substrate [5][6]. | ||
