Phosphofructokinase (PFK) catalyzes the phosphorylation of fructose-6-phosphate, forming fructose-1,6-bisphosphate. This phosphorylation is coupled to the hydrolysis of ATP, and is the key control step in glycolysis. PFK is made up of two domains: one large and one small. Each of these domains has 3 layers—2 layers of alpha helices with a central beta-sheet sandwiched between. There are a total of 13 alpha helices. The small domain's beta sheet is made up of four parallel strands. The larger domain's beta sheet is made up of seven strands. All of these strands are parallel except for the edge strands which are antiparallel. The two beta sheets point toward a cleft between the domains. This cleft forms the active site where Fru6P (or Fru 1,6 P) and ATP (or ADP) can bind. When ATP binds, the ribose hydroxyls hydrogen bond to Phe73, while Arg77, Met107, and Tyr41 form a slot which the adenine fits into. Furthermore, the beta-phosphate also forms hydrogen bonds to Gly104 and Ser105—two residues at the end of helix 5. When Fru6P binds it forms bonds with histidine, arginine, asparagine, glycine, and threonine residues. The 1-OH group of Fru6P is the phosphoryl acceptor. Upon binding of the substrate, it moves close enough to the gamma phosphate of ATP to attack it. Asp127, acting as a base, abstracts a proton from the 1-OH group. The phosphoryl group may now be transferred (with the magnesium ion still bound) from ATP to Fru6P. The Magnesium ion, initially bound to ATP, now forms a bridge between the 1-phosphate group of Fru1,6P, and the gamma phosphate of ADP. There is a third binding site. This site is not located in the active site. This is the effector site where allosteric inhibitors (such as PEP) and activators (such as ADP) may bind to regulate the enzyme. When ADP binds in this site, it is bound by four arginine residues and one lysine residue. Here the Mg2+ serves to bridge the alpha and beta phosphate groups of ADP. You may wish to manipulate this image yourself: Click and hold the left mouse button to rotate the image about the x and y axes. Rotate about the z axis by pressing the shift key and right mouse button together. The image may be translated along the x and y axes by pressing control and the right mouse button. By pressing shift and the left mouse button together, you may zoom the image in or out. Clicking the right mouse button on the image gives a menu which offers several choices, including spinning the image and changing the appearance and color of the molecule. For more information on this protein, consult: Shirakihara, Y. and Evans, P. (1988) Journal of Molecular Biology 204: 973-997.
PFK is made up of two domains: one large and one small. Each of these domains has 3 layers—2 layers of alpha helices with a central beta-sheet sandwiched between. There are a total of 13 alpha helices. The small domain's beta sheet is made up of four parallel strands. The larger domain's beta sheet is made up of seven strands. All of these strands are parallel except for the edge strands which are antiparallel. The two beta sheets point toward a cleft between the domains. This cleft forms the active site where Fru6P (or Fru 1,6 P) and ATP (or ADP) can bind. When ATP binds, the ribose hydroxyls hydrogen bond to Phe73, while Arg77, Met107, and Tyr41 form a slot which the adenine fits into. Furthermore, the beta-phosphate also forms hydrogen bonds to Gly104 and Ser105—two residues at the end of helix 5. When Fru6P binds it forms bonds with histidine, arginine, asparagine, glycine, and threonine residues. The 1-OH group of Fru6P is the phosphoryl acceptor. Upon binding of the substrate, it moves close enough to the gamma phosphate of ATP to attack it. Asp127, acting as a base, abstracts a proton from the 1-OH group. The phosphoryl group may now be transferred (with the magnesium ion still bound) from ATP to Fru6P. The Magnesium ion, initially bound to ATP, now forms a bridge between the 1-phosphate group of Fru1,6P, and the gamma phosphate of ADP. There is a third binding site. This site is not located in the active site. This is the effector site where allosteric inhibitors (such as PEP) and activators (such as ADP) may bind to regulate the enzyme. When ADP binds in this site, it is bound by four arginine residues and one lysine residue. Here the Mg2+ serves to bridge the alpha and beta phosphate groups of ADP. You may wish to manipulate this image yourself: Click and hold the left mouse button to rotate the image about the x and y axes. Rotate about the z axis by pressing the shift key and right mouse button together. The image may be translated along the x and y axes by pressing control and the right mouse button. By pressing shift and the left mouse button together, you may zoom the image in or out. Clicking the right mouse button on the image gives a menu which offers several choices, including spinning the image and changing the appearance and color of the molecule. For more information on this protein, consult: Shirakihara, Y. and Evans, P. (1988) Journal of Molecular Biology 204: 973-997.
Each of these domains has 3 layers—2 layers of alpha helices with a central beta-sheet sandwiched between. There are a total of 13 alpha helices. The small domain's beta sheet is made up of four parallel strands. The larger domain's beta sheet is made up of seven strands. All of these strands are parallel except for the edge strands which are antiparallel. The two beta sheets point toward a cleft between the domains. This cleft forms the active site where Fru6P (or Fru 1,6 P) and ATP (or ADP) can bind. When ATP binds, the ribose hydroxyls hydrogen bond to Phe73, while Arg77, Met107, and Tyr41 form a slot which the adenine fits into. Furthermore, the beta-phosphate also forms hydrogen bonds to Gly104 and Ser105—two residues at the end of helix 5. When Fru6P binds it forms bonds with histidine, arginine, asparagine, glycine, and threonine residues. The 1-OH group of Fru6P is the phosphoryl acceptor. Upon binding of the substrate, it moves close enough to the gamma phosphate of ATP to attack it. Asp127, acting as a base, abstracts a proton from the 1-OH group. The phosphoryl group may now be transferred (with the magnesium ion still bound) from ATP to Fru6P. The Magnesium ion, initially bound to ATP, now forms a bridge between the 1-phosphate group of Fru1,6P, and the gamma phosphate of ADP. There is a third binding site. This site is not located in the active site. This is the effector site where allosteric inhibitors (such as PEP) and activators (such as ADP) may bind to regulate the enzyme. When ADP binds in this site, it is bound by four arginine residues and one lysine residue. Here the Mg2+ serves to bridge the alpha and beta phosphate groups of ADP. You may wish to manipulate this image yourself: Click and hold the left mouse button to rotate the image about the x and y axes. Rotate about the z axis by pressing the shift key and right mouse button together. The image may be translated along the x and y axes by pressing control and the right mouse button. By pressing shift and the left mouse button together, you may zoom the image in or out. Clicking the right mouse button on the image gives a menu which offers several choices, including spinning the image and changing the appearance and color of the molecule. For more information on this protein, consult: Shirakihara, Y. and Evans, P. (1988) Journal of Molecular Biology 204: 973-997.
The two beta sheets point toward a cleft between the domains. This cleft forms the active site where Fru6P (or Fru 1,6 P) and ATP (or ADP) can bind. When ATP binds, the ribose hydroxyls hydrogen bond to Phe73, while Arg77, Met107, and Tyr41 form a slot which the adenine fits into. Furthermore, the beta-phosphate also forms hydrogen bonds to Gly104 and Ser105—two residues at the end of helix 5. When Fru6P binds it forms bonds with histidine, arginine, asparagine, glycine, and threonine residues. The 1-OH group of Fru6P is the phosphoryl acceptor. Upon binding of the substrate, it moves close enough to the gamma phosphate of ATP to attack it. Asp127, acting as a base, abstracts a proton from the 1-OH group. The phosphoryl group may now be transferred (with the magnesium ion still bound) from ATP to Fru6P. The Magnesium ion, initially bound to ATP, now forms a bridge between the 1-phosphate group of Fru1,6P, and the gamma phosphate of ADP. There is a third binding site. This site is not located in the active site. This is the effector site where allosteric inhibitors (such as PEP) and activators (such as ADP) may bind to regulate the enzyme. When ADP binds in this site, it is bound by four arginine residues and one lysine residue. Here the Mg2+ serves to bridge the alpha and beta phosphate groups of ADP. You may wish to manipulate this image yourself: Click and hold the left mouse button to rotate the image about the x and y axes. Rotate about the z axis by pressing the shift key and right mouse button together. The image may be translated along the x and y axes by pressing control and the right mouse button. By pressing shift and the left mouse button together, you may zoom the image in or out. Clicking the right mouse button on the image gives a menu which offers several choices, including spinning the image and changing the appearance and color of the molecule. For more information on this protein, consult: Shirakihara, Y. and Evans, P. (1988) Journal of Molecular Biology 204: 973-997.
When ATP binds, the ribose hydroxyls hydrogen bond to Phe73, while Arg77, Met107, and Tyr41 form a slot which the adenine fits into. Furthermore, the beta-phosphate also forms hydrogen bonds to Gly104 and Ser105—two residues at the end of helix 5. When Fru6P binds it forms bonds with histidine, arginine, asparagine, glycine, and threonine residues. The 1-OH group of Fru6P is the phosphoryl acceptor. Upon binding of the substrate, it moves close enough to the gamma phosphate of ATP to attack it. Asp127, acting as a base, abstracts a proton from the 1-OH group. The phosphoryl group may now be transferred (with the magnesium ion still bound) from ATP to Fru6P. The Magnesium ion, initially bound to ATP, now forms a bridge between the 1-phosphate group of Fru1,6P, and the gamma phosphate of ADP. There is a third binding site. This site is not located in the active site. This is the effector site where allosteric inhibitors (such as PEP) and activators (such as ADP) may bind to regulate the enzyme. When ADP binds in this site, it is bound by four arginine residues and one lysine residue. Here the Mg2+ serves to bridge the alpha and beta phosphate groups of ADP. You may wish to manipulate this image yourself: Click and hold the left mouse button to rotate the image about the x and y axes. Rotate about the z axis by pressing the shift key and right mouse button together. The image may be translated along the x and y axes by pressing control and the right mouse button. By pressing shift and the left mouse button together, you may zoom the image in or out. Clicking the right mouse button on the image gives a menu which offers several choices, including spinning the image and changing the appearance and color of the molecule. For more information on this protein, consult: Shirakihara, Y. and Evans, P. (1988) Journal of Molecular Biology 204: 973-997.
When Fru6P binds it forms bonds with histidine, arginine, asparagine, glycine, and threonine residues. The 1-OH group of Fru6P is the phosphoryl acceptor. Upon binding of the substrate, it moves close enough to the gamma phosphate of ATP to attack it. Asp127, acting as a base, abstracts a proton from the 1-OH group. The phosphoryl group may now be transferred (with the magnesium ion still bound) from ATP to Fru6P. The Magnesium ion, initially bound to ATP, now forms a bridge between the 1-phosphate group of Fru1,6P, and the gamma phosphate of ADP. There is a third binding site. This site is not located in the active site. This is the effector site where allosteric inhibitors (such as PEP) and activators (such as ADP) may bind to regulate the enzyme. When ADP binds in this site, it is bound by four arginine residues and one lysine residue. Here the Mg2+ serves to bridge the alpha and beta phosphate groups of ADP. You may wish to manipulate this image yourself: Click and hold the left mouse button to rotate the image about the x and y axes. Rotate about the z axis by pressing the shift key and right mouse button together. The image may be translated along the x and y axes by pressing control and the right mouse button. By pressing shift and the left mouse button together, you may zoom the image in or out. Clicking the right mouse button on the image gives a menu which offers several choices, including spinning the image and changing the appearance and color of the molecule. For more information on this protein, consult: Shirakihara, Y. and Evans, P. (1988) Journal of Molecular Biology 204: 973-997.
There is a third binding site. This site is not located in the active site. This is the effector site where allosteric inhibitors (such as PEP) and activators (such as ADP) may bind to regulate the enzyme. When ADP binds in this site, it is bound by four arginine residues and one lysine residue. Here the Mg2+ serves to bridge the alpha and beta phosphate groups of ADP. You may wish to manipulate this image yourself: Click and hold the left mouse button to rotate the image about the x and y axes. Rotate about the z axis by pressing the shift key and right mouse button together. The image may be translated along the x and y axes by pressing control and the right mouse button. By pressing shift and the left mouse button together, you may zoom the image in or out. Clicking the right mouse button on the image gives a menu which offers several choices, including spinning the image and changing the appearance and color of the molecule.
You may wish to manipulate this image yourself:
For more information on this protein, consult: Shirakihara, Y. and Evans, P. (1988) Journal of Molecular Biology 204: 973-997.