Definition
The local folding patterns in a peptide chain — alpha helices, beta sheets, and turns — stabilized by hydrogen bonds between backbone N–H and C=O groups.

Detailed Explanation

The local folding patterns in a peptide chain — alpha helices, beta sheets, and turns — stabilized by hydrogen bonds between backbone N–H and C=O groups. Secondary structure is the first level of three-dimensional organization above the primary sequence. The two main types are: α-helices (coiled structure, 3.6 residues per turn, i→i+4 hydrogen bonds) and β-sheets (extended strands aligned side-by-side, connected by inter-strand H-bonds).

Turns and loops connect helices and sheets. Secondary structure is predicted from sequence using algorithms like PSIPRED and JPred. Circular dichroism (CD) spectroscopy is the standard experimental method for measuring the secondary structure content of a peptide sample in solution.

Key Facts

  • The local folding patterns in a peptide chain — alpha helices, beta sheets, and turns — stabilized by hydrogen bonds between backbone N–H and C=O groups.
  • Secondary structure is the first level of three-dimensional organization above the primary sequence.
  • The two main types are: α-helices (coiled structure, 3.6 residues per turn, i→i+4 hydrogen bonds) and β-sheets (extended strands aligned side-by-side, connected by inter-strand H-bonds).
  • Turns and loops connect helices and sheets.
  • Secondary structure is predicted from sequence using algorithms like PSIPRED and JPred.
  • Circular dichroism (CD) spectroscopy is the standard experimental method for measuring the secondary structure content of a peptide sample in solution.
Related Terms Alpha Helix Beta Sheet Beta Turn Tertiary Structure Backbone Folding

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