Globular Proteins: Difference between revisions
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Other examples of protein having the characteristic of layered backbones will be divided into three categories - predominately α-helix, predominately β-sheets and mixed α-helix and β-sheets. | Other examples of protein having the characteristic of layered backbones will be divided into three categories - predominately α-helix, predominately β-sheets and mixed α-helix and β-sheets. | ||
==== Predominately | ==== Predominately Helices ==== | ||
The peptides in this class have a high contain of α-helix and because of the loops and turns which are present the α-helical strands will be antiparallel with respect to their adjacent strands. | The peptides in this class have a high contain of α-helix and because of the loops and turns which are present the α-helical strands will be antiparallel with respect to their adjacent strands. | ||
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==== Predominately β-Sheets ==== | ==== Predominately β-Sheets ==== | ||
* <scene name='Globular_Proteins/St_inhibitor/1'>Soybean trypsin inhibitor</scene> - As its name implies this protein inhibits the enzyme trypsin, and this inhibitory effect must be deactivated in the process of preparing soybeans for use in animal feed, so that the proteins in soybeans are hydrolyzed by trypsin. This protein is an example of the antiparallel β-barrel because the circular antiparallel sheet is barrel shaped. It is not as clearly defined as the parallel β-barrel, described above, but it is more common. You can look through the barrel whenever one of the open ends rotates to face the screen. An outer layer of α-helices is not present like it is in the parallel β-barrel, so the side chains projecting from the outer surface of the sheet are polar and make contact with water. | * <scene name='Globular_Proteins/St_inhibitor/1'>Soybean trypsin inhibitor</scene> - As its name implies this protein inhibits the enzyme trypsin, and this inhibitory effect must be deactivated in the process of preparing soybeans for use in animal feed, so that the proteins in soybeans are hydrolyzed by trypsin. This protein is an example of the antiparallel β-barrel because the circular antiparallel sheet is barrel shaped. It is not as clearly defined as the parallel β-barrel, described above, but it is more common. You can look through the barrel whenever one of the open ends rotates to face the screen. An outer layer of α-helices is not present like it is in the parallel β-barrel, so the side chains projecting from the outer surface of the sheet are polar and make contact with water. | ||
* <scene name='Globular_Proteins/Agguluttinin/1'>Aggluttinin</scene> - a mannose specific lectin from the bulb of snowdrop. A lectin is a protein that | * <scene name='Globular_Proteins/Agguluttinin/1'>Aggluttinin</scene> - a mannose specific lectin from the bulb of snowdrop. A lectin is a protein that binds oligsaccharides and glycoproteins and is involved in cell-cell recognition. Notice the prism like shape that is formed by the β-sheets. | ||
* <scene name='Globular_Proteins/Rieske/1'>Rieske protein</scene> - water soluble fragment (head) of the iron-sulfur protein from bovine heart. It is a component of Complex III of the mitochondrial respiratory chain. | * <scene name='Globular_Proteins/Rieske/1'>Rieske protein</scene> - water soluble fragment (head) of the iron-sulfur protein from bovine heart. It is a component of Complex III of the mitochondrial respiratory chain. | ||
* <scene name='Globular_Proteins/Lectin_r_s/1'>Lectin</scene> - from ''R. solanacearum''. It is an example of a protein having a quaternary structure, in this case it is trimeric - <scene name='Globular_Proteins/Lectin_r_s2/1'>three subunits</scene>. This type of structure is called a six-bladed propellor or β-propellor. Each subunit contributes two propellors. | * <scene name='Globular_Proteins/Lectin_r_s/1'>Lectin</scene> - from ''R. solanacearum''. It is an example of a protein having a quaternary structure, in this case it is trimeric - <scene name='Globular_Proteins/Lectin_r_s2/1'>three subunits</scene>. This type of structure is called a six-bladed propellor or β-propellor. Each subunit contributes two propellors. | ||