Sandbox Reserved 646: Difference between revisions
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== '''Mechanism''' == | == '''Mechanism''' == | ||
Arginine + H2O → Ornithine + Urea | Arginine + H2O → Ornithine + Urea | ||
The mechanism regarding arginase is highly important in the production of urea through the urea cycle. During the final step of the urea cycle, the amino acid arginine is present and needs to be cleaved in order for urea to be produced. Arginine is hydrolyzed and cleaved with the hydroxyl at the end of the amino group. We refer to this group as a guanidium end. The guanidium group is positively charged and has a high pKa. Therefore, it is willing to donate a proton since it has a hydrogen to give. First, the ligand will ionize the water to form hydroxide. The hydroxide now attacks the guanidine carbon and protons are transferred from the hydroxide to the substrate bridging. In the third and final step protons are transferred through a proton shuffle to create ornithine and urea. Afterwards, the urea is excreted through urine. Leaving the excess ornithine to be recycled through the final step in the cycle to react with citrulline and eliminate ammonia from the body. <ref> Roche, Victoria Improving Pharmacy Students' Understanding and Long-term Retention of Acid-Base Chemistry [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2690908/] </ref> | The mechanism regarding arginase is highly important in the production of urea through the urea cycle. During the final step of the urea cycle, the amino acid arginine is present and needs to be cleaved in order for urea to be produced. Arginine is hydrolyzed and cleaved with the hydroxyl at the end of the amino group. We refer to this group as a guanidium end. The guanidium group is positively charged and has a high pKa. Therefore, it is willing to donate a proton since it has a hydrogen to give. First, the ligand will ionize the water to form hydroxide. The hydroxide now attacks the guanidine carbon and protons are transferred from the hydroxide to the substrate bridging. In the third and final step protons are transferred through a proton shuffle to create ornithine and urea. Afterwards, the urea is excreted through urine. Leaving the excess ornithine to be recycled through the final step in the cycle to react with citrulline and eliminate ammonia from the body. <ref> Roche, Victoria Improving Pharmacy Students' Understanding and Long-term Retention of Acid-Base Chemistry [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2690908/] </ref> | ||
[[Image:arginase.gif]] | |||
