User:James D Watson/Structural Templates: Difference between revisions

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When two or more beta strands lie next to each other, forming hydrogen bonds between them, this is what is termed a <scene name='User:James_D_Watson/Structural_Templates/Secondary_structure_betasheet/1'>β-sheet</scene>. As the backbones need to come close together to interact and form a sheet, the <scene name='User:James_D_Watson/Structural_Templates/Secondary_structure_beta_sc/1'>sidechains are oriented away from the plane of the sheet</scene>. As the polypeptide chain is synthesised from the amino terminus to the carboxyl terminus it has a directionality (represented in the cartoon format as an arrowhead on each beta strand). β-sheets therefore occur in two varieties:<OL>

<LI><scene name='User:James_D_Watson/Structural_Templates/Secondary_structure_beta_ap/1'>Anti-parallel</scene> - here the beta strands aligned next to each other run in opposite directions. As the interacting carbonyls and amides align well, the hydrogen bonds appear to be straight.

<LI>Parallel - here the interacting strands run alongside each other and point in the same direction. In this conformation the carbonyl oxygen and the amides tend to be more staggered than in an anti-parallel sheet, therefore the hydrogen bonds tend to be angled.

<LI><scene name='User:James_D_Watson/Structural_Templates/Secondary_structure_beta_para/1'>Parallel</scene> - here the interacting strands run alongside each other and point in the same direction. In this conformation the carbonyl oxygen and the amides tend to be more staggered than in an anti-parallel sheet, therefore the hydrogen bonds tend to be angled. Also note the rare (i, i+2) bond within the lower strand.

</OL>

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 When two or more beta strands lie next to each other, forming hydrogen bonds between them, this is what is termed a <scene name='User:James_D_Watson/Structural_Templates/Secondary_structure_betasheet/1'>β-sheet</scene>. As the backbones need to come close together to interact and form a sheet, the <scene name='User:James_D_Watson/Structural_Templates/Secondary_structure_beta_sc/1'>sidechains are oriented away from the plane of the sheet</scene>. As the polypeptide chain is synthesised from the amino terminus to the carboxyl terminus it has a directionality (represented in the cartoon format as an arrowhead on each beta strand). β-sheets therefore occur in two varieties:<OL>
 <LI><scene name='User:James_D_Watson/Structural_Templates/Secondary_structure_beta_ap/1'>Anti-parallel</scene> - here the beta strands aligned next to each other run in opposite directions. As the interacting carbonyls and amides align well, the hydrogen bonds appear to be straight.
-<LI>Parallel - here the interacting strands run alongside each other and point in the same direction. In this conformation the carbonyl oxygen and the amides tend to be more staggered than in an anti-parallel sheet, therefore the hydrogen bonds tend to be angled.
+<LI><scene name='User:James_D_Watson/Structural_Templates/Secondary_structure_beta_para/1'>Parallel</scene> - here the interacting strands run alongside each other and point in the same direction. In this conformation the carbonyl oxygen and the amides tend to be more staggered than in an anti-parallel sheet, therefore the hydrogen bonds tend to be angled. Also note the rare (i, i+2) bond within the lower strand.
 </OL>
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