Sandbox Reserved 702: Difference between revisions
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==Two magnesium ions are coordinated by the catalytic site== | ==Two magnesium ions are coordinated by the catalytic site== | ||
<Structure load='1lvc' size=' | <Structure load='1lvc' size='300' frame='true' align='right' caption='Magnesium ions coordinated by D491, D498 and H577.' /> | ||
[[Adenylyl cyclase]] activity of the edema factor requires two magnesium ions. One of them is coordinated by <scene name='Sandbox_Reserved_702/Asp_and_his/2'>two aspartic residues (D491 and D493) and the histidine 577.</scene> | [[Adenylyl cyclase]] activity of the edema factor requires two magnesium ions. One of them is coordinated by <scene name='Sandbox_Reserved_702/Asp_and_his/2'>two aspartic residues (D491 and D493) and the histidine 577.</scene> | ||
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<scene name='Sandbox_Reserved_702/Histidine_351/1'>Histidine 351</scene> also plays a key role in the [[adenylyl cyclase]] reaction. Histidine is a crucial amino acid because its pKa (6.8) is close to pH of cytoplasm. | <scene name='Sandbox_Reserved_702/Histidine_351/1'>Histidine 351</scene> also plays a key role in the [[adenylyl cyclase]] reaction. Histidine is a crucial amino acid because its pKa (6.8) is close to pH of cytoplasm. | ||
It may intervene in proton-transfer reactions. Histidine 351 has a critical role in the catalytic activity of edema factor but is not a catalytic base. Since it is about 6.0 Å away from the 3'O of cAMP, its role is to allow a water molecule to enter between them. Histidine does not act as a general base (acceptor of 3'OH proton), but is facilitates an increase in the concentration of HO- ions in the proximity of the 3'OH group. <ref> PMID: 15719022</ref> | It may intervene in proton-transfer reactions. Histidine 351 has a critical role in the catalytic activity of edema factor but is not a catalytic base. Since it is about 6.0 Å away from the 3'O of cAMP, its role is to allow a water molecule to enter between them. Histidine does not act as a general base (acceptor of 3'OH proton), but is facilitates an increase in the concentration of HO- ions in the proximity of the 3'OH group. <ref> PMID: 15719022</ref> | ||
==Mechanism of adenylyl cyclase of edema factor== | ==Mechanism of adenylyl cyclase of edema factor== | ||
