Sandbox Reserved 322: Difference between revisions

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In general arginase is known to convert L-arginine into urea and L-ornithine, via hydrolysis, the proposed mechanism is adopted from Kanyo and colleagues as shown in figure 3<ref name="d"/>. In the first step of the hydrolytic mechanism, Asp 220 stabilizes the metal-bridging hydroxide ion with a hydrogen bond during a nucleophilic attack at the guanidinium carbon of arginine<ref name="b"/><ref name="d"/>. The resulting tetrahedral intermediate fall apart once a proton is transferred to the amino group of ornithine, and the proton transfer is mediated by Asp 220<ref name="b"/><ref name="d"/>. It is proposed that His 233 shuttles a proton from bulk solvent to the ε-amino group of ornithine, before the product dissociation, as well a water molecule displaces urea<ref name="b"/><ref name="d"/>. In addition, the metal coordination facilitates the ionization of this water molecule to regenerate a nucleophilic hydroxide ion<ref name="d"/>. During this process a proton transfer occurs to the bulk solvent and is mediated by shuttle-group His 233<ref name="b"/><ref name="d"/>.

Sandbox Reserved 322: Difference between revisions

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Revision as of 02:10, 4 April 2011 view source Brian Huang (talk \| contribs) 106 edits No edit summary ← Older edit		Revision as of 02:11, 4 April 2011 view source Brian Huang (talk \| contribs) 106 edits No edit summary Newer edit →
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	In general arginase is known to convert L-arginine into urea and L-ornithine, via hydrolysis, the proposed mechanism is adopted from Kanyo and colleagues as shown in figure 3<ref name="d"/>. In the first step of the hydrolytic mechanism, Asp 220 stabilizes the metal-bridging hydroxide ion with a hydrogen bond during a nucleophilic attack at the guanidinium carbon of arginine<ref name="b"/><ref name="d"/>. The resulting tetrahedral intermediate fall apart once a proton is transferred to the amino group of ornithine, and the proton transfer is mediated by Asp 220<ref name="b"/><ref name="d"/>. It is proposed that His 233 shuttles a proton from bulk solvent to the ε-amino group of ornithine, before the product dissociation, as well a water molecule displaces urea<ref name="b"/><ref name="d"/>. In addition, the metal coordination facilitates the ionization of this water molecule to regenerate a nucleophilic hydroxide ion<ref name="d"/>. During this process a proton transfer occurs to the bulk solvent and is mediated by shuttle-group His 233<ref name="b"/><ref name="d"/>.		In general arginase is known to convert L-arginine into urea and L-ornithine, via hydrolysis, the proposed mechanism is adopted from Kanyo and colleagues as shown in figure 3<ref name="d"/>. In the first step of the hydrolytic mechanism, Asp 220 stabilizes the metal-bridging hydroxide ion with a hydrogen bond during a nucleophilic attack at the guanidinium carbon of arginine<ref name="b"/><ref name="d"/>. The resulting tetrahedral intermediate fall apart once a proton is transferred to the amino group of ornithine, and the proton transfer is mediated by Asp 220<ref name="b"/><ref name="d"/>. It is proposed that His 233 shuttles a proton from bulk solvent to the ε-amino group of ornithine, before the product dissociation, as well a water molecule displaces urea<ref name="b"/><ref name="d"/>. In addition, the metal coordination facilitates the ionization of this water molecule to regenerate a nucleophilic hydroxide ion<ref name="d"/>. During this process a proton transfer occurs to the bulk solvent and is mediated by shuttle-group His 233<ref name="b"/><ref name="d"/>.