Globular Proteins: Difference between revisions
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Disulfide bonds and metal ion chelates can stabilize the tertiary structure in the absence of well organized layers which generate hydrophobic attractions. Some proteins are small in size and therefore do not have large amounts of backbone that can be organized into layers. Others have significant backbone, but the layers are not well organized and therefore are non-stabilizing. The attractions formed by metal ions chelates or disulfide bonds in these proteins are as important or more so than the hydrophobic interactions of the organized layers. Examples of both types of bonds will be given. | Disulfide bonds and metal ion chelates can stabilize the tertiary structure in the absence of well organized layers which generate hydrophobic attractions. Some proteins are small in size and therefore do not have large amounts of backbone that can be organized into layers. Others have significant backbone, but the layers are not well organized and therefore are non-stabilizing. The attractions formed by metal ions chelates or disulfide bonds in these proteins are as important or more so than the hydrophobic interactions of the organized layers. Examples of both types of bonds will be given. | ||
Some proteins or protein segments are [[Intrinsically_Disordered_Protein |intrinsically disordered]] (unstructured). Whether a complete protein or a protein segment since they are disordered, they can not be crystallized for x-ray crystallographic study. However, when these | Some proteins or protein segments are [[Intrinsically_Disordered_Protein |intrinsically disordered]] (unstructured). Whether a complete protein or a protein segment since they are disordered, they can not be crystallized for x-ray crystallographic study. However, when these peptides or peptide segments bind to other proteins they become ordered segments, and can be crystallized for x-ray crystallographic study. When these proteins bind to other proteins, since their conformations are extended and not compact, the binding occurs over relatively large surface areas of the binding proteins. Examples given below illustrate the extended conformations of the disordered peptides as well as the large binding surface. When viewing the unstructured peptides as unbound segments, realize that the conformation which is being displayed is not a disordered conformation but is the conformation of the bound segments. and therefore their conformations are determined by the binding site which they occupy. If the proteins or protein fragments were actually free and unbound, since they are unordered, the individual molecules would have a range of conformations and not just one. | ||
<StructureSection load='2ben' size='500' side='right' caption='' scene='Globular_Proteins/Insulin1/1'>__NOTOC__ | <StructureSection load='2ben' size='500' side='right' caption='' scene='Globular_Proteins/Insulin1/1'>__NOTOC__ | ||