Secondary Structure

Secondary Structure

Secondary Structure


The secondary structure refers to the conformation present at a local region of a polypeptide . A few types of secondary structure are particularly stable and occur widely in proteins. These include the α -helix and β -sheet conformations, which are both stabilized by hydrogen bonds . The α -helix is a rigid, rod-like structure that forms when a polypeptide chain twists into a helical conformation. Hydrogen bonds form between the amino (NH) group of one amino acid and the carbonyl (C = O) group of the amino acid four residues away. The amino acid side chains extend outward from the helix. In the β -sheet, two or more polypeptide chains (or two or more portions of the same chain) are arranged side by side to form a sheet. Hydrogen bonds form between the backbone amino groups and the carbonyl groups of adjacent chains. The sheets are pleated, not flat, and the amino acid side chains of adjacent amino acids extend from the pleat structure in opposite directions. In a protein, loops or bends can connect the secondary structures.

see also Primary Structure; Tertiary Structure.

Elizabeth S. Roberts-Kirchhoff

Bibliography

Creighton, Thomas E. (1993). Proteins: Structures and Molecular Properties, 2nd edition. New York: W. H. Freeman.

Internet Resources

Gorga, Frank. "Introduction to Protein Structure." Available from <http://webhost.bridgew.edu/fgorga>.

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Roberts-Kirchhoff, Elizabeth S.. "Secondary Structure." Chemistry: Foundations and Applications. 2004. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>.

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secondary structure

secondary structure The folding of a polypeptide or polynucleotide chain along one axis of the molecule; it is stabilized by the formation of intramolecular hydrogen bonds along the length of the chain. Compare PRIMARY STRUCTURE; QUATERNARY STRUCTURE; TERTIARY STRUCTURE.

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MICHAEL ALLABY. "secondary structure." A Dictionary of Zoology. 1999. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>.

MICHAEL ALLABY. "secondary structure." A Dictionary of Zoology. 1999. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O8-secondarystructure.html

MICHAEL ALLABY. "secondary structure." A Dictionary of Zoology. 1999. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O8-secondarystructure.html

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secondary structure

secondary structure Applied to proteins, the folding of a polypeptide or polynucleotide chain along one axis of the molecule; it is stabilized by the formation of intramolecular hydrogen bonds along the length of the chain.

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MICHAEL ALLABY. "secondary structure." A Dictionary of Plant Sciences. 1998. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>.

MICHAEL ALLABY. "secondary structure." A Dictionary of Plant Sciences. 1998. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O7-secondarystructure.html

MICHAEL ALLABY. "secondary structure." A Dictionary of Plant Sciences. 1998. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O7-secondarystructure.html

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secondary structure

secondary structure See protein.

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"secondary structure." A Dictionary of Biology. 2004. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>.

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