Sandbox Reserved 962: Difference between revisions

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<scene name='60/604481/Gtg/4'>A cap analog</scene> binds to the enzyme in a pocket near AdoHcy.{{clear}}
<scene name='60/604481/Gtg/4'>A cap analog</scene> binds to the enzyme in a pocket near AdoHcy.{{clear}}
<scene name='60/604481/Interaction_gtg/2'>6 amino acids</scene> (Tyr 145, Leu216, Leu217, Asp218, Ser219, Tyr284) are involded in the binding of the cap analog, more precisely they interact with guanine <scene name='60/604481/N1_n3_06_gtg/1'>N1, N3, and O6 atoms.</scene> and with the guanine exocyclic 2-NH2. {{clear}}
<scene name='60/604481/Interaction_gtg/2'>6 amino acids</scene> (Tyr 145, Leu216, Leu217, Asp218, Ser219, Tyr284) are involded in the binding of the cap analog, more precisely they interact with guanine <scene name='60/604481/N1_n3_06_gtg/1'>N1, N3, and O6 atoms.</scene> and with the gua2. <scene name='60/604481/N2_gtg/1'>guanine exocyclic 2-NH2.</scene>{{clear}}
The cap makes Van der Walls contacts with side chains from <scene name='60/604481/Vdw_gtg/1'>Leu216, Leu217, Asp218, Ser219.</scene> {{clear}}
The cap makes Van der Walls contacts with side chains from <scene name='60/604481/Vdw_gtg/1'>Leu216, Leu217, Asp218, Ser219.</scene> {{clear}}
GTP makes a hydrogen bond with <scene name='60/604481/Hb_gtg/1'>Tyr284</scene> and a  water mediated bond with <scene name='60/604481/Water_gtg/1'>Tyr145</scene>.
GTP makes a hydrogen bond with <scene name='60/604481/Hb_gtg/1'>Tyr284</scene> and a  water mediated bond with <scene name='60/604481/Water_gtg/1'>Tyr145</scene>.
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{{clear}}
{{clear}}
As we can see on the figure above<ref name="Hausmann S, Zheng S, Fabrega C, Schneller SW, Lima CD, Shuman S. Encephalitozoon cuniculi mRNA cap (guanine N-7) methyltransferase: methyl acceptor specificity, inhibition BY S-adenosylmethionine analogs, and structure-guided mutational analysis. J Biol Chem. 2005 May 27;280(21):20404-12. Epub 2005 Mar 9.">PMID:15760890 </ref> , the enzyme specifically binds to guanine.{{clear}}  
As we can see on the figure above<ref name="Hausmann S, Zheng S, Fabrega C, Schneller SW, Lima CD, Shuman S. Encephalitozoon cuniculi mRNA cap (guanine N-7) methyltransferase: methyl acceptor specificity, inhibition BY S-adenosylmethionine analogs, and structure-guided mutational analysis. J Biol Chem. 2005 May 27;280(21):20404-12. Epub 2005 Mar 9.">PMID:15760890 </ref> , the enzyme specifically binds to guanine.{{clear}}  
This specificity is achieved through different recognitions. The N-1 atom of adenine is unprotonated, this prevent the interaction of adenine with Ecm1. Ecm1 contact the <scene name='60/604481/N1_n3_06_gtg/1'>O6 atom</scene> of guanine and permit an additional discrimination between guanine and adenine. Moreover the fact that ITP is not a substrate for Ecm1 show that the interactions between Ecm1 and guanine exocyclic 2-NH2 are important for substrate binding. {{clear}}
This specificity is achieved through different recognitions. The N-1 atom of adenine is unprotonated, this prevent the interaction of adenine with Ecm1. Ecm1 contact the <scene name='60/604481/N1_n3_06_gtg/1'>O6 atom</scene> of guanine and permit an additional discrimination between guanine and adenine. Moreover the fact that ITP is not a substrate for Ecm1 show that the interactions between Ecm1 and <scene name='60/604481/N2_gtg/1'>guanine exocyclic 2-NH2</scene> are important for substrate binding. {{clear}}
We also remark that the methyltransferase is not able to discrminate between ribose and desoxyribose nucleoside sugars.
We also remark that the methyltransferase is not able to discrminate between <scene name='60/604481/Ribose_gtg/1'>ribose</scene> and desoxyribose nucleoside sugars.