Sandbox136: Difference between revisions
From Proteopedia
Jump to navigationJump to search
Elie Peillon (talk | contribs) |
Elie Peillon (talk | contribs) |
||
| Line 17: | Line 17: | ||
Anum-II has a length of 134 amino-acids. The phospholipase is formed by a short N-terminalαhelix (between residues 2-12), a 2nd αhelix (residues 40-55), two-stranded antiparallel <scene name='Sandbox136/Feuillets/1'>sheet</scene> linked thanks to a βwing (74-85) and a 3rd αhelix (residues 90-107). The 3rd αhelix is bound to the 2nd αhelix (in an antiparallele way) thanks to disulfure bonds ([Cys 44-Cys 105] and [Cys 51-Cys 98]) and thus form a <scene name='Sandbox136/Stabilisation/1'>rigid platform</scene>. The protein is stabilized by 5 other disulfides bonds [Cys 27-Cys 125], [Cys 29-Cys 45] [Cys 50 Cys 134] [Cys 61-Cys 91] [Cys84-Cys96]. Alignment of Anum-II with other PLA2 have revealed that the positions of amino-acid residues which form the catalytic apparatus are conserved (His48,Tyr52, Tyr73 and Asp99) except for Asp49 which is replaced by Lys 49. | Anum-II has a length of 134 amino-acids. The phospholipase is formed by a short N-terminalαhelix (between residues 2-12), a 2nd αhelix (residues 40-55), two-stranded antiparallel <scene name='Sandbox136/Feuillets/1'>sheet</scene> linked thanks to a βwing (74-85) and a 3rd αhelix (residues 90-107). The 3rd αhelix is bound to the 2nd αhelix (in an antiparallele way) thanks to disulfure bonds ([Cys 44-Cys 105] and [Cys 51-Cys 98]) and thus form a <scene name='Sandbox136/Stabilisation/1'>rigid platform</scene>. The protein is stabilized by 5 other disulfides bonds [Cys 27-Cys 125], [Cys 29-Cys 45] [Cys 50 Cys 134] [Cys 61-Cys 91] [Cys84-Cys96]. Alignment of Anum-II with other PLA2 have revealed that the positions of amino-acid residues which form the catalytic apparatus are conserved (His48,Tyr52, Tyr73 and Asp99) except for Asp49 which is replaced by Lys 49. | ||
The structure of the protein has revealed the presence of an anion-binding site between <scene name='Sandbox136/Anion/2'>R34</scene>, <scene name='Sandbox136/Anion/2'>K53</scene> and a water molecule. Sulfate ion is anchored thanks to hydrogen bonds between: | The structure of the protein has revealed the presence of an anion-binding site between <scene name='Sandbox136/Anion/2'>R34</scene>, <scene name='Sandbox136/Anion/2'>K53</scene> and a water molecule (see Figure 3). Sulfate ion is anchored thanks to hydrogen bonds between: | ||
+O1 atom | +O1 atom with R34 Nε , K53 Nζ and a solvent water molecule. | ||
+O2 atom | +O2 atom with the NH main chain of R34 | ||
+O4 atom | +O4 atom with K53 Nζ and R34 Nη2 | ||
[[Image:Anion_Interactions.jpg | thumb]] | [[Image:Anion_Interactions.jpg | thumb]] | ||
This anion-binding site is supposed to play a role in the fixation of inhibitors but his function remains unknown. In the crystallization state (pH5), the protein is in a | This anion-binding site is supposed to play a role in the fixation of inhibitors but his function remains unknown. In the crystallization state (pH5), the protein is in a monomeric state whereas in a solution at physiological pH a dimerization occurs . The dimerization happened thanks to interactions at the interface of the N-terminal and β-wing regions . Studies have shown that Anum-II is active only in the dimeric state. | ||
== ''' Method of Determination''' == | == ''' Method of Determination''' == | ||
