Alpha helix: Difference between revisions
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==Types of proteins and folds that contain alpha helices== | ==Types of proteins and folds that contain alpha helices== | ||
===Alpha helices in soluble (globular) proteins=== | ===Alpha helices in soluble (globular) proteins=== | ||
The first two protein structure to be determined, [[myoglobin]] and [[hemoglobin]], consists mainly of alpha helices. Researchers were surprised to see how random the orientation of helices seemed to be. Other all alpha-helical proteins show bundles of nearly parallel helices. In structures that have beta sheets and alpha helices, one common fold is a single beta sheet that is sandwiched by layers of alpha helices on either side (for example [[Carboxypeptidase A]]. When an alpha helix runs along the surface of the protein, one side of it will show polar side chains (solvent accessible) while the other side will show non-polar side chains (part of the hydrophobic core). The alpha helix fits nicely into the major groove of DNA. Many common DNA-binding motifs, such as the helix-turn-helix (e.g. [[FIS protein]]) or the zinc finger motif (e.g. engineered zinf finger protein [[2i13]], feature a short alpha helix that binds to the major groove of DNA. | The first two protein structure to be determined, [[myoglobin]] and [[hemoglobin]], consists mainly of alpha helices. Researchers were surprised to see how random the orientation of helices seemed to be. Other all alpha-helical proteins show bundles of nearly parallel (or antiparallel) helices (e.g. bacterial cytochrome c' [[1e83]]. In structures that have beta sheets and alpha helices, one common fold is a single beta sheet that is sandwiched by layers of alpha helices on either side (for example [[Carboxypeptidase A]]. When an alpha helix runs along the surface of the protein, one side of it will show polar side chains (solvent accessible) while the other side will show non-polar side chains (part of the hydrophobic core). The alpha helix fits nicely into the major groove of DNA. Many common DNA-binding motifs, such as the helix-turn-helix (e.g. [[FIS protein]]) or the zinc finger motif (e.g. engineered zinf finger protein [[2i13]], feature a short alpha helix that binds to the major groove of DNA. | ||
===Alpha helices in transmembrane proteins=== | ===Alpha helices in transmembrane proteins=== | ||