Sandbox Reserved 196: Difference between revisions
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Slight differences include changes in crystal packing, as the RNase B crystals have two slightly asymmetrical units. The crystals are dimeric with two separate molecules, I and II, which are linked by a salt bridge at Asp-121 and Arg-85. This linkage determines the orientation of the two molecules in relation to one another. Not only does a salt bridge link this dimer-type molecule, but other ions also interact via cross-linkage to stabilize the structure <ref name="third" />. | Slight differences include changes in crystal packing, as the RNase B crystals have two slightly asymmetrical units. The crystals are dimeric with two separate molecules, I and II, which are linked by a salt bridge at Asp-121 and Arg-85. This linkage determines the orientation of the two molecules in relation to one another. Not only does a salt bridge link this dimer-type molecule, but other ions also interact via cross-linkage to stabilize the structure <ref name="third" />. | ||
The crystallization of RNase B, in complex with sequence DNA, provided the structure of the active site when bound to nucleic acids. The active site, composed of <scene name='Sandbox_Reserved_196/Secondary_structure/11' target='1rbj'>His-12, Lys-41 and His-119</scene> and found in both molecules I and II of RNase B is very similar to the active site of RNase A. A difference is the <scene name='Sandbox_Reserved_196/Rbb_basic/9' target='1rbb'>residues 15-23</scene> (in top applet), which are very flexible and can open up or close off the active site. Molecules I and II are slightly asymmetrical, and the most noticeable difference between the two is the position of the Lys-66. This residue, which is present in both molecules, is much closer to the active site in molecule II. This is important because ions bind to Lys-66, like the DNA, making them accessible to the active site. Even though the crystallization of the structure has been successful, it has not been an aid to providing the mechanism by which RNase B has the catalytic activity to hydrolyze double stranded RNA.<ref name="third" />. <scene name='Sandbox_Reserved_196/Secondary_structure/8' target='1rbj'>(Return to original scene)</scene> | The crystallization of RNase B, in complex with sequence DNA, provided the structure of the active site when bound to nucleic acids. The active site, composed of <scene name='Sandbox_Reserved_196/Secondary_structure/11' target='1rbj'>His-12, Lys-41 and His-119</scene> and found in both molecules I and II of RNase B is very similar to the active site of RNase A. A difference between RNase A and RNase B is the <scene name='Sandbox_Reserved_196/Rbb_basic/9' target='1rbb'>residues 15-23</scene> (in top applet), which are very flexible and can open up or close off the active site. Molecules I and II are slightly asymmetrical, and the most noticeable difference between the two is the position of the <scene name='Sandbox_Reserved_196/Secondary_structure/12'>Lys-66</scene>. This residue, which is present in both molecules, is much closer to the active site in molecule II. This is important because ions bind to Lys-66, like the DNA, making them accessible to the active site. While the crystalline packing of molecules I and II differ slighlty, their active sites bind substrate in the same manner. Even though the crystallization of the structure has been successful, it has not been an aid to providing the mechanism by which RNase B has the catalytic activity to hydrolyze double stranded RNA.<ref name="third" />. <scene name='Sandbox_Reserved_196/Secondary_structure/8' target='1rbj'>(Return to original scene)</scene> | ||
== References == | == References == | ||
