Secondary structure: Difference between revisions

Secondary structure of a protein refers to the three-dimensional structure of local segments of a protein.  Each type of secondary structure has segments that have a repeating conformational pattern which is produced by a repeating pattern of values for the [[Psi and Phi Angles|phi and psi torsional angles]].  For this reason on a [[Ramachandran Plots|Ramachandran plot]] for a particular secondary structure the values for phi and psi are located at a particular area of the plot. There are three important second structures - helix, β-sheets and turns, and there are several variations of each one of them. Alpha helix, pi helix and 3₁₀ helix are the three types of helices with the alpha helix being the most important.  The characteristics of these three helices are given at [[Helices in Proteins]]. Jmol has a standard of coloring them <font color=#FF0080>alpha helix</font>, <font color=#600080>pi helix</font> and <font color=#A00080>3₁₀ helix</font> as shown in [[Helices in Proteins]]. for example alpha helices and beta sheets are secondary structure. The structure on the right of a human transferrin n-lobe mutant (PDB code [[1dtg]]) is shown in cartoon backbone representation to highlight its secondary structure, with alpha-helices in magenta and beta-sheets in yellow.