Aspartate Transcarbamoylase (ATCase): Difference between revisions
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== Contents== | |||
== Structure == | == Structure == | ||
ATCase consists of two <scene name='58/581338/Catalytic_subunits/1'>catalytic</scene> trimers and three <scene name='58/581338/Regulatory_subunits/1'>regulatory</scene> dimers that are completely separable units. It should be noted that this scene is only looking at one set of regulatory and catalytic subunits not all of them for the sake of visualization. It has been documented that the subunits can even combine when mixed together, reconstituting the enzyme. The two catalytic trimers are arranged on top of each other, with three dimers of the regulatory chains combining them. Significant interactions between the regulatory dimers and catalytic trimers occur; such as catalytic trimer chains contacting structural domains in the regulatory unit that are stabilized by a <scene name='58/581338/Zn_domain/3'>zinc</scene> atom bound to four cysteine residues. ATCase is largely alpha helical with large changes in quaternary structure occurring (trimers move 12 Angstroms apart and rotate approximately 10 degrees) upon <scene name='58/581338/Pala/1'>PALA</scene> binding (a bisubstrate analog that resembles an intermediate). The <scene name='58/581338/Pala_interactions/1'>PALA interactions</scene> are as shown. | ATCase consists of two <scene name='58/581338/Catalytic_subunits/1'>catalytic</scene> trimers and three <scene name='58/581338/Regulatory_subunits/1'>regulatory</scene> dimers that are completely separable units. It should be noted that this scene is only looking at one set of regulatory and catalytic subunits not all of them for the sake of visualization. It has been documented that the subunits can even combine when mixed together, reconstituting the enzyme. The two catalytic trimers are arranged on top of each other, with three dimers of the regulatory chains combining them. Significant interactions between the regulatory dimers and catalytic trimers occur; such as catalytic trimer chains contacting structural domains in the regulatory unit that are stabilized by a <scene name='58/581338/Zn_domain/3'>zinc</scene> atom bound to four cysteine residues. ATCase is largely alpha helical with large changes in quaternary structure occurring (trimers move 12 Angstroms apart and rotate approximately 10 degrees) upon <scene name='58/581338/Pala/1'>PALA</scene> binding (a bisubstrate analog that resembles an intermediate). The <scene name='58/581338/Pala_interactions/1'>PALA interactions</scene> are as shown. | ||