Sandbox Reserved 194: Difference between revisions

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<Structure load='1RTA' size='450' frame='true' align='right' caption='Insert caption here' scene='Sandbox_Reserved_194/1rta_just_dt/1' />
<Structure load='1RTA' size='450' frame='true' align='right' caption='Insert caption here' scene='Sandbox_Reserved_194/1rta_just_dt/1' />
[[Image:1RTA_zoom.png|thumb|left|250px|Thymidylic acid tetramer complexed with ribonuclease A]]
[[Image:1RTA_zoom.png|thumb|left|250px|Thymidylic acid tetramer complexed with ribonuclease A]]


To determine the structural characteristics of RNA substrate binding to RNase A, X-ray crystallography was used to image inhibitory DNA tetramers bound to the enzyme.  DNA lacks the 2’OH essential to RNA cleavage, making the complex more conducive to crystallography.  In previous studies, <scene name='Sandbox_Reserved_194/1rta_structure/1'>
== Headline text ==
the RNase A - thymidylic acid tetramer (d(pT)4) complex</scene> has provided information into the specificity of the binding pocket subunits, B0, B1, B2 and B3.  Many interactions observed in this complex occur between amino acid residues and the nucleic acid backbone such as hydrogen bonding between the A1 ribose and Thr78.  Because of the interactions with the N3 and Thr45 in the B1 position, it appears this site is exclusive to pyrimidines.


To determine the structural characteristics of RNA substrate binding to RNase A, X-ray crystallography was used to image inhibitory DNA tetramers bound to the enzyme.  DNA lacks the 2′OH essential to RNA cleavage, making the complex more conducive to crystallography.  In previous studies, <scene name='Sandbox_Reserved_194/1rta_structure/1'>
the RNase A - thymidylic acid tetramer (d(pT)4) complex</scene> has provided information into the specificity of the binding pocket subunits, B0, B1, B2 and B3.  Many interactions observed in this complex occur between amino acid residues and the nucleic acid backbone such as hydrogen bonding between the A1 ribose and Thr78.  Because of the interactions with the N3 and Thr45 in the B1 position, it appears this site is exclusive to pyrimidines. ‘<ref>PMID:1429575</ref>’   


[[Image:1RCN_zoom.png|thumb|left|250px|ApTpApApG complexed with ribonuclease A]]
Further binding pocket characterization was accomplished using the oglionucleotide <scene name='Sandbox_Reserved_194/1rcn_just_dtda/1'>d(ApTpApApG)</scene>.   
Further binding pocket characterization was accomplished using the oglionucleotide <scene name='Sandbox_Reserved_194/1rcn_just_dtda/1'>d(ApTpApApG)</scene>.   
While binding of other nucleobases to the B2 and B3 sites is possible, the imaging of this <scene name='Sandbox_Reserved_194/1rcn_structure/2'>complex </scene>elucidated the  preferences for adenosine bases at these two positions.  RNase A establishes <scene name='Sandbox_Reserved_194/1rcn_his/4'>pi stacking between His119 and A3 </scene>in addition to hydrogen bonding between <scene name='Sandbox_Reserved_194/1rcn_hydrogen_bonding/1'>Asn71-A3, Gln69-A3 and Gln69-A4</scene>.
While binding of other nucleobases to the B2 and B3 sites is possible, the imaging of this <scene name='Sandbox_Reserved_194/1rcn_structure/2'>complex </scene>elucidated the  preferences  
[[Image:1RCN_zoom.png|thumb|left|250px|ApTpApApG complexed with ribonuclease A]]
for adenosine bases at these two positions.  RNase A establishes <scene name='Sandbox_Reserved_194/1rcn_his/4'>pi stacking between His119 and A3 </scene>in addition to hydrogen bonding between <scene name='Sandbox_Reserved_194/1rcn_hydrogen_bonding/1'>Asn71-A3, Gln69-A3 and Gln69-A4</scene>. ‘<ref>PMID:8063789</ref>’   
 


‘<references/>’
== References ==
<references/>
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