Introduction to protein structure: Difference between revisions
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===Turns and loops=== | ===Turns and loops=== | ||
Secondary structures are often connected by turns and loops, such as:<UL> | Secondary structures are often connected by turns and loops, such as:<UL> | ||
<LI>'''<scene name=' | <LI>'''<scene name='57/575866/Secondary_structure_betaturn/1'>Beta Turns</scene>''' - originally defined by the one hydrogen bond common to all (an i, i+3 hydrogen bond) but some modern descriptions do not require a hydrogen bond. | ||
<LI>'''Alpha turns''' - the simplest of all motifs and is characterized by one (i, i+4) hydrogen bond. It is found as part of the hydrogen bonding network of alpha helices as well as occurring on its own. | <LI>'''Alpha turns''' - the simplest of all motifs and is characterized by one (i, i+4) hydrogen bond. It is found as part of the hydrogen bonding network of alpha helices as well as occurring on its own. | ||
<LI>'''<scene name='57/575866/Secondary_structure_paperclip/1'>Paperclip/Schellman Motifs</scene>''' - a common motif found at the C-termini of alpha helices which is essentially a reverse turn that breaks the alpha helix out of its cycle. It is characterized by the presence of a left handed residue and two hydrogen bonds: an i, i+3 bond and an i, i+5 bond. | <LI>'''<scene name='57/575866/Secondary_structure_paperclip/1'>Paperclip/Schellman Motifs</scene>''' - a common motif found at the C-termini of alpha helices which is essentially a reverse turn that breaks the alpha helix out of its cycle. It is characterized by the presence of a left handed residue and two hydrogen bonds: an i, i+3 bond and an i, i+5 bond. | ||