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 56 KDa (18). The monomer unit of GDH is essentially two trimers of six identical subunits containing three distinct domains; the Glutamate (Glu) binding domain at the N terminus, the NAD binding doman, and the antenna domain, separated by a large active site cleft (9). The overall | GDH is a homohexamer of 505 residues with a molecular weight of 56 KDa (18). The monomer unit of GDH is essentially two trimers of six identical subunits containing three distinct domains; the Glutamate (Glu) binding domain at the N terminus, the NAD binding doman, and the antenna domain, separated by a large active site cleft (9). 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 (18) | ||
The NAD+ binding domains are located on top of the glutamate binding domain. These NAD+ binding domains rotate down upon the substrate and coenzyme to initiate catalysis. The NAD+ binding domain contains a forty eight-residue “antenna” that extends from the top of the NAD+ binding domain. This antenna undergoes conformational changes as the cleft of the active site opens and closes (2). Both of the domains are positioned differently in GDH. When GDH is not bound by glutamate its cleft is open, however when GDH is bound by glutamate it is closed. This position difference between the two domains allows the cleft to be closed, which brings the C4 of the nicotinamide ring and the alpha carbon of the glutamate substrate into the appropriate orientation for a hydride transfer to occur. | The NAD+ binding domains are located on top of the glutamate binding domain. These NAD+ binding domains rotate down upon the substrate and coenzyme to initiate catalysis. The NAD+ binding domain contains a forty eight-residue “antenna” that extends from the top of the NAD+ binding domain. This antenna undergoes conformational changes as the cleft of the active site opens and closes (2). Both of the domains are positioned differently in GDH. When GDH is not bound by glutamate its cleft is open, however when GDH is bound by glutamate it is closed. This position difference between the two domains allows the cleft to be closed, which brings the C4 of the nicotinamide ring and the alpha carbon of the glutamate substrate into the appropriate orientation for a hydride transfer to occur. | ||
