- 1. [NA] The margin of the auricle; a folded rim of cartilage forming the upper part of the anterior, the superior, and the greater part of the posterior edges of the auricle. 2. A line in the shape of a coil (or a spring, or the threads on a bolt), each point being equidistant from a straight line that is the axis of the cylinder in which each point of the h. lies; often, mistakenly, applied to a spiral. [L. fr. G. h., a coil]- 310 h. a type of right-handed h. found in small pieces in a number of proteins; has three amino acid residues per turn.- 3.613 h. SYN: α h..- α h. the helical (commonly right-handed) form present in many proteins, deduced by Pauling and Corey from x-ray diffraction studies of proteins such as α-keratin; the h. is stabilized by hydrogen bonds between, e.g., R2C=O and HNR2′ groups (symbolized by the center dot in R2CO HNR2′) of different eupeptide bonds. In a true α h., there are 3.6 amino acid residues per turn of the h. and a rise of 1.5 Å per residue. SYN: 3.613 h., Pauling-Corey h..- collagen h. an extended left-handed h. resulting from the high levels of glycine, l-proline, and l-hydroxyproline present in the collagens. There are 3.3 amino acid s per turn of the h.. Three of those left-handed helices form a triple superhelix that is right-handed.- DNA h. SYN: Watson-Crick h..- double h. SYN: Watson-Crick h..- π h. a rare right-handed h. found only in small portions of certain proteins. Stabilized by similar hydrogen bonds as in an α h.; there are 4.3 amino acid residues per turn of this h..- Pauling-Corey h. SYN: α h..- triple h. the superhelix formed (right-handed) from three individual collagen helices (each being left-handed).- Watson-Crick h. the helical structure assumed by two strands of deoxyribonucleic acid, held together throughout their length by hydrogen bonds between bases on opposite strands, referred to as Watson-Crick base pairing. See base pair. SYN: DNA h., double h., twin h..
* * *1) the incurved rim of the external ear2) a curve traced on a cylinder by the rotation of a point crossing its right sections at a constant oblique angle broadly SPIRAL (2) see ALPHA-HELIX, DOUBLE HELIX
* * *n.the outer curved fleshy ridge of the pinna of the outer ear.
* * *He·lix (heґliks) a genus of snails of the family Helicidae, including some of the common garden snails.
Medical dictionary. 2011.