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  2. Helix - Wikipedia

    en.wikipedia.org/wiki/Helix

    The pitch of a helix is the height of one complete helix turn, measured parallel to the axis of the helix. A double helix consists of two (typically congruent) helices with the same axis, differing by a translation along the axis. [3] A circular helix (i.e. one with constant radius) has constant band curvature and constant torsion. The slope of ...

  3. Protein secondary structure - Wikipedia

    en.wikipedia.org/wiki/Protein_secondary_structure

    If the helix or sheet hydrogen bonding pattern is too short they are designated as T or B, respectively. Other protein secondary structure assignment categories exist (sharp turns, Omega loops, etc.), but they are less frequently used. Secondary structure is defined by hydrogen bonding, so the

  4. 310 helix - Wikipedia

    en.wikipedia.org/wiki/310_helix

    The amino acids in a 3 10-helix are arranged in a right-handed helical structure. Each amino acid corresponds to a 120° turn in the helix (i.e., the helix has three residues per turn), and a translation of 2.0 Å (0.20 nm) along the helical axis, and has 10 atoms in the ring formed by making the hydrogen bond.

  5. Alpha helix - Wikipedia

    en.wikipedia.org/wiki/Alpha_helix

    Three-dimensional structure [1] of an alpha helix in the protein crambin. An alpha helix (or α-helix) is a sequence of amino acids in a protein that are twisted into a coil (a helix). The alpha helix is the most common structural arrangement in the secondary structure of proteins. It is also the most extreme type of local structure, and it is ...

  6. Helix angle - Wikipedia

    en.wikipedia.org/wiki/Helix_angle

    The efficiency can be plotted versus the helix angle for a constant friction, as shown in the adjacent diagram. The maximum efficiency is a helix angle between 40 and 45 degrees, however a reasonable efficiency is achieved above 15°. Due to difficulties in forming the thread, helix angle greater than 30° are rarely used.

  7. Pi helix - Wikipedia

    en.wikipedia.org/wiki/Pi_helix

    A pi helix (or π-helix) is a type of secondary structure found in proteins. Discovered by crystallographer Barbara Low in 1952 [ 1 ] and once thought to be rare, short π-helices are found in 15% of known protein structures and are believed to be an evolutionary adaptation derived by the insertion of a single amino acid into an α-helix . [ 2 ]

  8. Anatomical terminology - Wikipedia

    en.wikipedia.org/wiki/Anatomical_terminology

    Basically, it covers the gross anatomy and the microscopic (histology and cytology) of living beings. It involves both development anatomy and the anatomy of the adult. It also includes comparative anatomy between different species. The vocabulary is extensive, varied and complex, and requires a systematic presentation.

  9. Triple helix - Wikipedia

    en.wikipedia.org/wiki/Triple_helix

    The collagen triple helix is a triple helix formed from three separate protein helices, spiraling around the same axis. In the fields of geometry and biochemistry, a triple helix (pl.: triple helices) is a set of three congruent geometrical helices with the same axis, differing by a translation along the axis. This means that each of the ...