Protein secondary stucture: Difference between revisions
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=== Alpha-Helix === | === Alpha-Helix === | ||
A alpha-helix is a right handed helix that resembles a right handed spiral staircase. An alpha helix contains hydrogen bonding between the N-H group of every peptide bond and C=O groups that are next to a peptide bond<ref>B.Alberts et al. (2014) Essencial Cell Biology 4th edition, Gartland Science, New York</ref>. these are usually loacated 4 [[ | A alpha-helix is a right handed helix that resembles a right handed spiral staircase. An alpha helix contains hydrogen bonding between the N-H group of every peptide bond and C=O groups that are next to a peptide bond<ref>B.Alberts et al. (2014) Essencial Cell Biology 4th edition, Gartland Science, New York</ref>. these are usually loacated 4 [[Amino acid|amino acids]] away from each other but in the same chain. This is what produces the spiraling structure of the alpha-helix. There is 3.6 amino acid residues in each coil turn in the alpha helix.<ref>Berg.J, Stryer.L, Tymoczko J, Biochemistry, seventh edition, WH Freeman, 2012, page 39</ref> | ||
The most common known helix structure is that of [[DNA|DNA]], where 2 alpha helicies are wound around each other with complimentary base paring between them holding them together. | The most common known helix structure is that of [[DNA|DNA]], where 2 alpha helicies are wound around each other with complimentary base paring between them holding them together. | ||
=== Beta-Sheet === | === Beta-Sheet === | ||
Revision as of 21:07, 27 November 2014
The secondary structure of a protein describes the way in which a poly peptide chain of amino acids are folded.
These secondary structures can be separated into 2 section alpha-helicies and a beta-sheet formation, these describe the level of organisation of the specific foldin patterens.
Alpha-Helix
A alpha-helix is a right handed helix that resembles a right handed spiral staircase. An alpha helix contains hydrogen bonding between the N-H group of every peptide bond and C=O groups that are next to a peptide bond[1]. these are usually loacated 4 amino acids away from each other but in the same chain. This is what produces the spiraling structure of the alpha-helix. There is 3.6 amino acid residues in each coil turn in the alpha helix.[2]
The most common known helix structure is that of DNA, where 2 alpha helicies are wound around each other with complimentary base paring between them holding them together.
Beta-Sheet
The beta-sheet is where one chain of amino acids, form a parallel or antiparallel folded structure with hydrogen bonding between the ajacent strands of the fold, between N-H and C=O groups.[3]
The antiparallel structure is stronger due to the almost perfect lining up of the strands to make hydrogen bonds that form directly perpendiculatr to the running strand. The parallel structure isn't as strong howevre is still a very ridged structure.