2hji: Difference between revisions

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==Overview==

Acireductone dioxygenase (ARD) catalyzes different reactions between O2, and 1,2-dihydroxy-3-oxo-5-(methylthio)pent-1-ene (acireductone) depending, upon the metal bound in the active site. Ni2+ -ARD cleaves acireductone to, formate, CO and methylthiopropionate. If Fe2+ is bound (ARD'), the same, substrates yield methylthioketobutyrate and formate. The two forms differ, in structure, and are chromatographically separable. Paramagnetism of Fe2+, renders the active site of ARD' inaccessible to standard NMR methods. The, structure of ARD' has been determined using Fe2+ binding parameters, determined by X-ray absorption spectroscopy and NMR restraints from H98S, ARD, a metal-free diamagnetic protein that is isostructural with ARD'., ARD' retains the beta-sandwich fold of ARD, but a structural entropy, switch increases order at one end of a two-helix system that bisects the, beta-sandwich and decreases order at the other upon interconversion of ARD, and ARD', causing loss of the C-terminal helix in ARD' and rearrangements, of residues involved in substrate orientation in the active site.

Acireductone dioxygenase (ARD) catalyzes different reactions between O2 and 1,2-dihydroxy-3-oxo-5-(methylthio)pent-1-ene (acireductone) depending upon the metal bound in the active site. Ni2+ -ARD cleaves acireductone to formate, CO and methylthiopropionate. If Fe2+ is bound (ARD'), the same substrates yield methylthioketobutyrate and formate. The two forms differ in structure, and are chromatographically separable. Paramagnetism of Fe2+ renders the active site of ARD' inaccessible to standard NMR methods. The structure of ARD' has been determined using Fe2+ binding parameters determined by X-ray absorption spectroscopy and NMR restraints from H98S ARD, a metal-free diamagnetic protein that is isostructural with ARD'. ARD' retains the beta-sandwich fold of ARD, but a structural entropy switch increases order at one end of a two-helix system that bisects the beta-sandwich and decreases order at the other upon interconversion of ARD and ARD', causing loss of the C-terminal helix in ARD' and rearrangements of residues involved in substrate orientation in the active site.

==About this Structure==

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[[Category: Klebsiella oxytoca]]

[[Category: Single protein]]

[[Category: Chai, S.C.]]

[[Category: Chai, S C.]]

[[Category: Ju, T.]]

[[Category: Maroney, M.J.]]

[[Category: Maroney, M J.]]

[[Category: Pochapsky, T.C.]]

[[Category: Pochapsky, T C.]]

[[Category: FE2]]

[[Category: dioxygenase]]

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[[Category: structural entropy]]

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@@ Line 4: / Line 4: @@
 ==Overview==
-Acireductone dioxygenase (ARD) catalyzes different reactions between O2, and 1,2-dihydroxy-3-oxo-5-(methylthio)pent-1-ene (acireductone) depending, upon the metal bound in the active site. Ni2+ -ARD cleaves acireductone to, formate, CO and methylthiopropionate. If Fe2+ is bound (ARD'), the same, substrates yield methylthioketobutyrate and formate. The two forms differ, in structure, and are chromatographically separable. Paramagnetism of Fe2+, renders the active site of ARD' inaccessible to standard NMR methods. The, structure of ARD' has been determined using Fe2+ binding parameters, determined by X-ray absorption spectroscopy and NMR restraints from H98S, ARD, a metal-free diamagnetic protein that is isostructural with ARD'., ARD' retains the beta-sandwich fold of ARD, but a structural entropy, switch increases order at one end of a two-helix system that bisects the, beta-sandwich and decreases order at the other upon interconversion of ARD, and ARD', causing loss of the C-terminal helix in ARD' and rearrangements, of residues involved in substrate orientation in the active site.
+Acireductone dioxygenase (ARD) catalyzes different reactions between O2 and 1,2-dihydroxy-3-oxo-5-(methylthio)pent-1-ene (acireductone) depending upon the metal bound in the active site. Ni2+ -ARD cleaves acireductone to formate, CO and methylthiopropionate. If Fe2+ is bound (ARD'), the same substrates yield methylthioketobutyrate and formate. The two forms differ in structure, and are chromatographically separable. Paramagnetism of Fe2+ renders the active site of ARD' inaccessible to standard NMR methods. The structure of ARD' has been determined using Fe2+ binding parameters determined by X-ray absorption spectroscopy and NMR restraints from H98S ARD, a metal-free diamagnetic protein that is isostructural with ARD'. ARD' retains the beta-sandwich fold of ARD, but a structural entropy switch increases order at one end of a two-helix system that bisects the beta-sandwich and decreases order at the other upon interconversion of ARD and ARD', causing loss of the C-terminal helix in ARD' and rearrangements of residues involved in substrate orientation in the active site.
 ==About this Structure==
@@ Line 14: / Line 14: @@
 [[Category: Klebsiella oxytoca]]
 [[Category: Single protein]]
-[[Category: Chai, S.C.]]
+[[Category: Chai, S C.]]
 [[Category: Ju, T.]]
-[[Category: Maroney, M.J.]]
+[[Category: Maroney, M J.]]
-[[Category: Pochapsky, T.C.]]
+[[Category: Pochapsky, T C.]]
 [[Category: FE2]]
 [[Category: dioxygenase]]
@@ Line 25: / Line 25: @@
 [[Category: structural entropy]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jan 29 20:22:29 2008''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:42:32 2008''