Sandbox Reserved 761: Difference between revisions
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==Glutamate Dehydrogenase Structure== | ==Glutamate Dehydrogenase Structure== | ||
GDH is a homohexamer of 505 residues with a molecular weight of 55.638 KDa | GDH is a homohexamer of 505 residues with a molecular weight of 55.638 KDa <ref>http://www.rcsb.org/pdb</ref>. The overall <scene name='56/564037/Secondary_structures/1'>secondary structures</scene> of GDH is composed of eighteen <font color="#ff0080">'''alpha helices'''</font> and thirteen <font color="#d0a000">'''beta strands'''</font>, which are both parallel and anti-parallel and flanked by a layer of alpha helices <ref>http://www.rcsb.org/pdb</ref>. | ||
The monomer unit of GDH is essentially two trimers of six identical subunits containing <scene name='56/564037/Domains/1'>two distinct domains</scene>—the Glutamate (Glu) binding domain at the N terminus and the NAD binding doman—and a 48-residue antenna-like projection that extends from the top of each NAD binding domain, separated by a large active site cleft (9). The antenna consists of an ascending helix and a descending random coil strand that contains a small α-helix toward the C-terminal end of the strand. Domain I is made up of residues 4-181 and 400-421, and is responsible for directing the assembly of the subunits into a hexamer. Domain I is colored blue. Domain II makes up the glutamate-binding domain, and is composed of mainly beta sheets involving residues 182-399, which is colored orange <ref>PMID:16285734</ref>. Domain I is also called the C-domain, whereas the Domain II is called the N-domain <ref>PMID:11258921</ref>. The NAD+ cofactor binds at the C-terminal end of the parallel beta strands in the N-domain, lying in the cleft between the N and C-domains. The glutamate substrate binds deep in this cleft, with the side chain of the glutamate lying in a pocket on the enzyme surface. Residues 193-204, and 383-393 are essential for the glutamate to bind in the cleft (1). These residues are colored <scene name='56/564037/Domains1/1'>green</scene> <ref>PMID:9405044</ref>. | The monomer unit of GDH is essentially two trimers of six identical subunits containing <scene name='56/564037/Domains/1'>two distinct domains</scene>—the Glutamate (Glu) binding domain at the N terminus and the NAD binding doman—and a 48-residue antenna-like projection that extends from the top of each NAD binding domain, separated by a large active site cleft (9). The antenna consists of an ascending helix and a descending random coil strand that contains a small α-helix toward the C-terminal end of the strand. Domain I is made up of residues 4-181 and 400-421, and is responsible for directing the assembly of the subunits into a hexamer. Domain I is colored blue. Domain II makes up the glutamate-binding domain, and is composed of mainly beta sheets involving residues 182-399, which is colored orange <ref>PMID:16285734</ref>. Domain I is also called the C-domain, whereas the Domain II is called the N-domain <ref>PMID:11258921</ref>. The NAD+ cofactor binds at the C-terminal end of the parallel beta strands in the N-domain, lying in the cleft between the N and C-domains. The glutamate substrate binds deep in this cleft, with the side chain of the glutamate lying in a pocket on the enzyme surface. Residues 193-204, and 383-393 are essential for the glutamate to bind in the cleft (1). These residues are colored <scene name='56/564037/Domains1/1'>green</scene> <ref>PMID:9405044</ref>. | ||
