Hydrophobic helices are made up of mostly non-polar residues. Shown in the upper left-hand corner is a hydrophobic helix found in citrate synthase. Hydrophilic helices, on the other hand, are made up almost entirely of polar residues. Shown in the lower left-hand corner is a hydrophilic helix found in calmodulin. Amphipathic helices are helices that have hydrophobic residues arranged on one side and hydrophilic resides on the other side. Thus, these helices have a polar face and a non-polar face. A prime example of an amphipathic helix is one of the helices found in flavodoxin (shown above). Click here to see the helices as ball and stick models: Hydrophobic helix of citrate synthase Hydrophilic helix of calmodulin Amphipathic helix of flavodoxin Click here to see the helices as ribbon models: Hydrophobic helix of citrate synthase Hydrophilic helix of calmodulin Amphipathic helix of flavodoxin Click here to see the helices as space-fillling models in the context of the rest of the protein: Hydrophobic helix of citrate synthase Hydrophilic helix of calmodulin Amphipathic helix of flavodoxin Notice that the environment of the helix determines its character. In calmodulin, the helix we examined is surrounded by solvent and thus must be predominantly hydrophilic. In flavodoxin, the helix in question lies on the surface of the protein, and thus the inward-directed face is hydrophobic and the outward-directed face is hydrophilic. The helix we examined in citrate synthase also appears to be a surface helix, but it is predominantly hydrophobic. Why?? The answer is that citrate synthase is a homodimer, and the helix we have examined lies on the subunit-subunit interface. Thus this helix lies in the hydrophobic core of the dimer, and it must necessarily be hydrophobic! You may wish to manipulate these images 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.
Hydrophilic helices, on the other hand, are made up almost entirely of polar residues. Shown in the lower left-hand corner is a hydrophilic helix found in calmodulin. Amphipathic helices are helices that have hydrophobic residues arranged on one side and hydrophilic resides on the other side. Thus, these helices have a polar face and a non-polar face. A prime example of an amphipathic helix is one of the helices found in flavodoxin (shown above). Click here to see the helices as ball and stick models: Hydrophobic helix of citrate synthase Hydrophilic helix of calmodulin Amphipathic helix of flavodoxin Click here to see the helices as ribbon models: Hydrophobic helix of citrate synthase Hydrophilic helix of calmodulin Amphipathic helix of flavodoxin Click here to see the helices as space-fillling models in the context of the rest of the protein: Hydrophobic helix of citrate synthase Hydrophilic helix of calmodulin Amphipathic helix of flavodoxin Notice that the environment of the helix determines its character. In calmodulin, the helix we examined is surrounded by solvent and thus must be predominantly hydrophilic. In flavodoxin, the helix in question lies on the surface of the protein, and thus the inward-directed face is hydrophobic and the outward-directed face is hydrophilic. The helix we examined in citrate synthase also appears to be a surface helix, but it is predominantly hydrophobic. Why?? The answer is that citrate synthase is a homodimer, and the helix we have examined lies on the subunit-subunit interface. Thus this helix lies in the hydrophobic core of the dimer, and it must necessarily be hydrophobic! You may wish to manipulate these images 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.
Amphipathic helices are helices that have hydrophobic residues arranged on one side and hydrophilic resides on the other side. Thus, these helices have a polar face and a non-polar face. A prime example of an amphipathic helix is one of the helices found in flavodoxin (shown above). Click here to see the helices as ball and stick models: Hydrophobic helix of citrate synthase Hydrophilic helix of calmodulin Amphipathic helix of flavodoxin Click here to see the helices as ribbon models: Hydrophobic helix of citrate synthase Hydrophilic helix of calmodulin Amphipathic helix of flavodoxin Click here to see the helices as space-fillling models in the context of the rest of the protein: Hydrophobic helix of citrate synthase Hydrophilic helix of calmodulin Amphipathic helix of flavodoxin Notice that the environment of the helix determines its character. In calmodulin, the helix we examined is surrounded by solvent and thus must be predominantly hydrophilic. In flavodoxin, the helix in question lies on the surface of the protein, and thus the inward-directed face is hydrophobic and the outward-directed face is hydrophilic. The helix we examined in citrate synthase also appears to be a surface helix, but it is predominantly hydrophobic. Why?? The answer is that citrate synthase is a homodimer, and the helix we have examined lies on the subunit-subunit interface. Thus this helix lies in the hydrophobic core of the dimer, and it must necessarily be hydrophobic! You may wish to manipulate these images 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.
Click here to see the helices as ball and stick models: Hydrophobic helix of citrate synthase Hydrophilic helix of calmodulin Amphipathic helix of flavodoxin Click here to see the helices as ribbon models: Hydrophobic helix of citrate synthase Hydrophilic helix of calmodulin Amphipathic helix of flavodoxin Click here to see the helices as space-fillling models in the context of the rest of the protein: Hydrophobic helix of citrate synthase Hydrophilic helix of calmodulin Amphipathic helix of flavodoxin Notice that the environment of the helix determines its character. In calmodulin, the helix we examined is surrounded by solvent and thus must be predominantly hydrophilic. In flavodoxin, the helix in question lies on the surface of the protein, and thus the inward-directed face is hydrophobic and the outward-directed face is hydrophilic. The helix we examined in citrate synthase also appears to be a surface helix, but it is predominantly hydrophobic. Why?? The answer is that citrate synthase is a homodimer, and the helix we have examined lies on the subunit-subunit interface. Thus this helix lies in the hydrophobic core of the dimer, and it must necessarily be hydrophobic! You may wish to manipulate these images 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.
Click here to see the helices as ribbon models: Hydrophobic helix of citrate synthase Hydrophilic helix of calmodulin Amphipathic helix of flavodoxin Click here to see the helices as space-fillling models in the context of the rest of the protein: Hydrophobic helix of citrate synthase Hydrophilic helix of calmodulin Amphipathic helix of flavodoxin Notice that the environment of the helix determines its character. In calmodulin, the helix we examined is surrounded by solvent and thus must be predominantly hydrophilic. In flavodoxin, the helix in question lies on the surface of the protein, and thus the inward-directed face is hydrophobic and the outward-directed face is hydrophilic. The helix we examined in citrate synthase also appears to be a surface helix, but it is predominantly hydrophobic. Why?? The answer is that citrate synthase is a homodimer, and the helix we have examined lies on the subunit-subunit interface. Thus this helix lies in the hydrophobic core of the dimer, and it must necessarily be hydrophobic! You may wish to manipulate these images 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.
Click here to see the helices as space-fillling models in the context of the rest of the protein: Hydrophobic helix of citrate synthase Hydrophilic helix of calmodulin Amphipathic helix of flavodoxin Notice that the environment of the helix determines its character. In calmodulin, the helix we examined is surrounded by solvent and thus must be predominantly hydrophilic. In flavodoxin, the helix in question lies on the surface of the protein, and thus the inward-directed face is hydrophobic and the outward-directed face is hydrophilic. The helix we examined in citrate synthase also appears to be a surface helix, but it is predominantly hydrophobic. Why?? The answer is that citrate synthase is a homodimer, and the helix we have examined lies on the subunit-subunit interface. Thus this helix lies in the hydrophobic core of the dimer, and it must necessarily be hydrophobic! You may wish to manipulate these images 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.
Notice that the environment of the helix determines its character. In calmodulin, the helix we examined is surrounded by solvent and thus must be predominantly hydrophilic. In flavodoxin, the helix in question lies on the surface of the protein, and thus the inward-directed face is hydrophobic and the outward-directed face is hydrophilic.
The helix we examined in citrate synthase also appears to be a surface helix, but it is predominantly hydrophobic. Why??
The answer is that citrate synthase is a homodimer, and the helix we have examined lies on the subunit-subunit interface. Thus this helix lies in the hydrophobic core of the dimer, and it must necessarily be hydrophobic!
You may wish to manipulate these images yourself: