Sandbox Reserved 962: Difference between revisions
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== | == Biological role== | ||
== Structure == | == Structure == | ||
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<scene name='60/604481/Gtg/2'>A cap analog</scene> binds to the enzyme in a pocket near the AdoHcy. | <scene name='60/604481/Gtg/2'>A cap analog</scene> binds to the enzyme in a pocket near the AdoHcy. | ||
<scene name='60/604481/Interaction_gtg/1'>6 amino acids</scene> are involded in the binding of the cap analog. | <scene name='60/604481/Interaction_gtg/1'>6 amino acids</scene> (Tyr 145, Leu216, Leu217, Asp218, Ser219, Tyr284) are involded in the binding of the cap analog. | ||
The cap makes Van der Walls contacts, hydrogen bond and water mediated bond. | The cap makes Van der Walls contacts, hydrogen bond and water mediated bond. | ||
The enzyme specifically binds to guanine. This specificity is achieved through the recognition by the enzyme residues through hydrogen bonds of the guanine N1, N3, and O6 atoms. | |||
<ref name="Fabrega C, Hausmann S, Shen V, Shuman S, Lima CD. Structure and mechanism of mRNA cap (guanine-N7) methyltransferase. Mol Cell. 2004 Jan 16;13(1):77-89. ">PMID:14731396</ref> | |||
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<scene name='60/604481/Interaction_sah/1'>10 amino acids</scene> (Lys54, Gly72, Asp78, Asp94, Ile95, Asp122, Ser124, Gln140, Phe141, Ser142) are involved in the stabilisation of AdoHcys. | <scene name='60/604481/Interaction_sah/1'>10 amino acids</scene> (Lys54, Gly72, Asp78, Asp94, Ile95, Asp122, Ser124, Gln140, Phe141, Ser142) are involved in the stabilisation of AdoHcys. | ||
The interactions between AdoHcys and the enzyme are made of : hydrogen bonds, Van der Walls interactions,electrostatic interaction and water mediated contact. | The interactions between AdoHcys and the enzyme are made of : hydrogen bonds, Van der Walls interactions,electrostatic interaction and water mediated contact. | ||
<ref | <ref name="Fabrega C, Hausmann S, Shen V, Shuman S, Lima CD. Structure and mechanism of mRNA cap (guanine-N7) methyltransferase. Mol Cell. 2004 Jan 16;13(1):77-89. ">PMID:14731396</ref> | ||
== | == Mechanism== | ||
This enzyme catalyse N-methyl transfer from AdoMet (S-adenosylmethionine) to GpppRNA, this reaction produce 7-methyl-GpppRNA and AdoHcy. | |||
We remark that the enzyme do not stabilize the transition state of the chemical reaction, do not promote the activation of the nucleophile or the explusion of the leaving group. mRNA Cap Methyltransferase orientates the substrates to facilitate the methyl transfer. | |||
== References == | == References == | ||
<references/> | <references/> | ||
