Sandbox Reserved 774: Difference between revisions
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=Structure= | =Structure= | ||
Has a chain structure with 2.4 A resolution, and 2.9 A resolution with a | Has a chain structure with 2.4 A resolution, and 2.9 A resolution with a co-factor (acetyl-CoA).<ref name=Shiva/> The method used to determine the structure was [[X-ray crystallography]]. Sedimentation and crystal structure analysis clearly shows that Hpa2 is dimeric in solution and tetramerizes in the unit crystal. The crystal structure of the oligomer reveals that two Hpa2 dimers are held together by interaction between the bound acetyl-CoA molecules. The average B-factor value is 23.9 (<scene name='56/564050/Bakhbone_mainechain/1' target=0>main chain</scene>) with a 25.4 <scene name='56/564050/Sidechain/2' target=0>side chain</scene>. The R-factor is 0.19. <ref name=Shiva/> Core fold features include four conserved sequence motifs of the GNAT family and comprises a central highly curved five stranded <scene name='56/564050/Beta_sheets/1' target=0>Beta sheets</scene> (β1-β5) surrounded on both sides by helical segments (α1 and α3).<ref name=Shiva/> | ||
[[Image:Chain.jpg.png | thumb | '''Figure 1.''' Sequence of Hpa2.]] | [[Image:Chain.jpg.png | thumb | '''Figure 1.''' Sequence of Hpa2.]] | ||
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Most of the hydrogen bonding between Hpa2 and its co-factor AcCoA are highly conserved and occur via the main-chain groups, not the side-chains. This explains the uniformity of the binds with the co-factors, despite the low degree of sequence conservation. The conserved main-chain contacts seen in a segment of Motif A forms a loop before and around the first turn of the helix in Motif A. This is found in residues | Most of the hydrogen bonding between Hpa2 and its co-factor AcCoA are highly conserved and occur via the main-chain groups, not the side-chains. This explains the uniformity of the binds with the co-factors, despite the low degree of sequence conservation. The conserved main-chain contacts seen in a segment of Motif A forms a loop before and around the first turn of the helix in Motif A. This is found in residues | ||
<scene name='56/564050/Residues_100-104/3' target=0>100-104</scene>. Most of the residues in this loop contribute to a series of hydrogen bonds between the Alpha and Beta phosphate oxygen atoms via main-chain groups. This includes a conserved solvent molecule interaction. This loops was not located within Hpa2 in the absence of its co-factor, indicating that this region is formed upon co-factor binding. It appears that this area of interactions is a vital determinant for the binding of AcCoA. <ref name=Shiva/> | <scene name='56/564050/Residues_100-104/3' target=0>100-104</scene>. Most of the residues in this loop contribute to a series of hydrogen bonds between the Alpha and Beta phosphate oxygen atoms via main-chain groups. This includes a conserved solvent molecule interaction. This loops was not located within Hpa2 in the absence of its co-factor, indicating that this region is formed upon <scene name='56/564050/Test/1' target=1>co-factor</scene> binding. It appears that this area of interactions is a vital determinant for the binding of AcCoA. <ref name=Shiva/> | ||
==Active Site== | ==Active Site== | ||
