Ketosteroid Isomerase: Difference between revisions
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β-strand 1 is connected to β-strand 2 via a <scene name='User:Laura_M._Haynes/Sandbox_1/Cis_loop/1'>four residue linkage</scene> (Pro39 to Ser42) with Pro39 being in a cis-conformation. Two examples of [http://en.wikipedia.org/wiki/Turn_%28biochemistry%29 type-II β-turns] can also be observed in KSI-between β-stands 3 & 4 (<scene name='User:Laura_M._Haynes/Sandbox_1/Turn_1/1'>Ala75-Asn76→see figure</scene>) and β-strands 4 & 5 (<scene name='User:Laura_M._Haynes/Sandbox_1/Turn_2/1'>Gln89-Gly90</scene>). A loop structure (<scene name='User:Laura_M._Haynes/Sandbox_1/Loop2/1'>Asn105-Val107</scene>) also connects β-strands 5 and 6. | β-strand 1 is connected to β-strand 2 via a <scene name='User:Laura_M._Haynes/Sandbox_1/Cis_loop/1'>four residue linkage</scene> (Pro39 to Ser42) with Pro39 being in a cis-conformation. Two examples of [http://en.wikipedia.org/wiki/Turn_%28biochemistry%29 type-II β-turns] can also be observed in KSI-between β-stands 3 & 4 (<scene name='User:Laura_M._Haynes/Sandbox_1/Turn_1/1'>Ala75-Asn76→see figure</scene>) and β-strands 4 & 5 (<scene name='User:Laura_M._Haynes/Sandbox_1/Turn_2/1'>Gln89-Gly90</scene>). A loop structure (<scene name='User:Laura_M._Haynes/Sandbox_1/Loop2/1'>Asn105-Val107</scene>) also connects β-strands 5 and 6. | ||
===Dimer Interface=== | ===Dimer Interface=== | ||
The biologically active unit of KSI is a 2-fold symmetric dimer in which the two chains are packed together via hydrophobic and electrostatic interactions between the "back faces" of the β-sheets. The curved β-sheets on each of the monomers expose convex faces to each other, forming well-defined interactions. In their NMR structure of KSI, Massiah et al. identified interchain hydrophobic interactions (A), as well, a number of polar residues (B) located within the dimer interface. | The biologically active unit of KSI is a 2-fold symmetric dimer in which the two chains are packed together via hydrophobic and electrostatic interactions between the "back faces" of the β-sheets. The curved β-sheets on each of the monomers expose convex faces to each other, forming well-defined interactions. In their NMR structure of KSI, Massiah et al. <ref name="Massiah">PMID:9778345</ref> identified interchain hydrophobic interactions (A), as well, a number of polar residues (B) located within the dimer interface. | ||
[[Image:dimer_interface.png|thumb|center|760px|'''Interactions at KSI's dimer interface''' (A) Hydrophobic residues. (B) Hydrophillic residues.]] | [[Image:dimer_interface.png|thumb|center|760px|'''Interactions at KSI's dimer interface''' (A) Hydrophobic residues. (B) Hydrophillic residues.]] | ||
