Lesson: beta turns: Difference between revisions
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# Glycine and proline occur relatively often in beta turns and play distinct special roles | # Glycine and proline occur relatively often in beta turns and play distinct special roles | ||
See the discussion tab for learning and teaching notes. | See the [[Talk:Lesson:_beta_turns|discussion tab]] for learning and teaching notes. | ||
==Turns in 3D== | ==Turns in 3D== | ||
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<StructureSection load='' size='350' side='right' caption='' scene='10/1072233/Turn_2mhr/2'> | <StructureSection load='' size='350' side='right' caption='' scene='10/1072233/Turn_2mhr/2'> | ||
===Basic features=== | ===Basic features=== | ||
The interactive Jmol window on the right shows a beta turn (<scene name='10/1072233/Turn_2mhr/2'>reload initial scene</scene>) indicating the short distance between the first and the fourth alpha carbon. Because of this short distance, the polypeptide takes a sharp turn, sometimes also called a reverse turn. There are many types of beta turns, and they differ in the phi and psi angles of residues two and three<ref>PMID:7756980</ref>. Some turns feature a <scene name='10/1072233/Turn_2mhr/4'>hydrogen bond</scene> between residues one and four (like the one shown here) and others don't. | The interactive Jmol window on the right shows a beta turn (<scene name='10/1072233/Turn_2mhr/2'>reload initial scene</scene>) indicating the short distance between the first and the fourth alpha carbon. Because of this short distance, the polypeptide takes a sharp turn, sometimes also called a reverse turn. There are many types of beta turns, and they differ in the [[Tutorial:Ramachandran_principle_and_phi_psi_angles|phi and psi angles]] of residues two and three<ref>PMID:7756980</ref>. Some turns feature a <scene name='10/1072233/Turn_2mhr/4'>hydrogen bond</scene> between residues one and four (like the one shown here) and others don't. | ||
===Beta turns in the context of other secondary structures=== | ===Beta turns in the context of other secondary structures=== | ||
The repetitive secondary structure elements (alpha helices and beta strands) go in a single direction. Turns change the direction of the main chain, allowing them to connect alpha helices and beta strands at the surface of a globular protein. Of the six main chain hydrogen bonding partners of a turn, a maximum of two are engaged in hydrogen bonding, and turns are rarely found in the hydrophobic core. Below are three different protein folds highlighting the role of turns and their positions within a fold. | The repetitive secondary structure elements ([[Alpha helix|alpha helices]] and [[Sheets in Proteins|beta strands]]) go in a single direction. Turns change the direction of the main chain, allowing them to connect alpha helices and beta strands at the surface of a globular protein. Of the six main chain hydrogen bonding partners of a turn, a maximum of two are engaged in hydrogen bonding, and turns are rarely found in the hydrophobic core. Below are three different protein folds highlighting the role of turns and their positions within a fold. | ||
====Turns in an all-alpha protein==== | ====Turns in an all-alpha protein==== | ||
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You can explore more turns at betaturn.com, which allows you to browse for turns of a specific type, and contains a lot of information and explanations. | You can explore more turns at [https://betaturn.com/ betaturn.com], which allows you to browse for turns of a specific type, and contains a lot of information and explanations. | ||
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Further reading | Further reading | ||
* [[Turns in Proteins]] | * [[Turns in Proteins]] | ||
* [ | * [[Alpha helix]] | ||
* [[Sheets in Proteins]] | |||
==References== | ==References== | ||
<references/> | <references/> | ||
