Ketosteroid Isomerase: Difference between revisions
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==Structure== | ==Structure== | ||
Ketosteroid isomerase exits as a 28 kDa homodimeric protein, in which the two dimers related to each other via hydrophobic and electrostatic interactions.<ref name="Wu" /> Each monomer consists of a curved <scene name='User:Laura_M._Haynes/Sandbox_1/Beta_sheets/1'>beta-sheets</scene> and three <scene name='User:Laura_M._Haynes/Sandbox_1/Alpha_helices/1'>alpha-helices</scene>. These secondary structures define a conical closed barrel geometry, with one open and one closed end, and create a deep pocket in which the active site resides.<ref name="Ha" />,<ref name="Cho">PMID:9622484 </ref> This unique geometry is shared by several other proteins (scytalone dehydratase, nuclear transport factor 2, and naphthalene 1,2-dioxygenase), however, these molecules do not share functional or sequence homology. It is speculated that this unique protein structure may enable better binding of hydrophobic substrates such as steroids.<ref name="Ha" /> | Ketosteroid isomerase exits as a 28 kDa homodimeric protein, in which the two dimers related to each other via hydrophobic and electrostatic interactions.<ref name="Wu" /> Each monomer consists of a curved <scene name='User:Laura_M._Haynes/Sandbox_1/Beta_sheets/1'>beta-sheets</scene> and three <scene name='User:Laura_M._Haynes/Sandbox_1/Alpha_helices/1'>alpha-helices</scene>. These secondary structures define a conical closed barrel geometry, with one open and one closed end, and create a deep pocket in which the active site resides.<ref name="Ha" />,<ref name="Cho">PMID:9622484 </ref> This unique geometry is shared by several other proteins (scytalone dehydratase, nuclear transport factor 2, and naphthalene 1,2-dioxygenase), however, these molecules do not share functional or sequence homology. It is speculated that this unique protein structure may enable better binding of hydrophobic substrates such as steroids.<ref name="Ha" /> | ||
[[Image:top2.png|thumb|center|500px|'''Topology diagram of KSI's structure''' Helices A, B, and C are in an antiparallel arrangement. The six β-strands form a mixed β-sheet.]] | [[Image:top2.png|thumb|center|500px|'''Topology diagram of KSI's structure''' Helices A, B, and C are in an antiparallel arrangement. The six β-strands form a mixed β-sheet.]] | ||
