Michael Pikaart/Biochem StructureIntro: Difference between revisions
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Here is a look at one of the GCN4 polypeptides in contact with DNA. Two side chains in proximity to the DNA are shown as balls, the DNA in stick form. | Here is a look at one of the GCN4 polypeptides in contact with DNA. Two side chains in proximity to the DNA are shown as balls, the DNA in stick form. | ||
== Beta sheet == | == Beta sheet == | ||
A second type of structure commonly found in proteins is the beta sheet. Unlike the helix, there is not a rotational component to this structure. Because of this, a single length of beta sheet structure cannot complete intra-strand hydrogen bonding. Rather, the hydrogen bonding that stabilizes beta sheet structures occurs between neighboring strands. These strands can either be parallel or antiparallel. In either orientation, there must be a stretch of linker polypeptide in a continuous polypeptide - this may be as short as two amino acids in a so-called beta turn, or a longer stretch of polypeptide with its own secondary structure. A protein which has significant beta sheet secondary structure is the protease elastase: <applet load=' | A second type of structure commonly found in proteins is the beta sheet. Unlike the helix, there is not a rotational component to this structure. Because of this, a single length of beta sheet structure cannot complete intra-strand hydrogen bonding. Rather, the hydrogen bonding that stabilizes beta sheet structures occurs between neighboring strands. These strands can either be parallel or antiparallel. In either orientation, there must be a stretch of linker polypeptide in a continuous polypeptide - this may be as short as two amino acids in a so-called beta turn, or a longer stretch of polypeptide with its own secondary structure. A protein which has significant beta sheet secondary structure is the protease elastase: <applet load='1est' size='400' frame='true' align='right' caption='Insert caption here' /> | ||
<scene name='Pikaart_Sandbox_1/Beta_sheets_from_elastase/1'>Beta sheet sections from elastase</scene> | |||
