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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 ]
Protein secondary structure is the local spatial conformation of the polypeptide backbone excluding the side chains. [ 1 ] The two most common secondary structural elements are alpha helices and beta sheets, though beta turns and omega loops occur as well.
A machine screw. The right-handed helix (cos t, sin t, t) for 0 ≤ t ≤ 4π with arrowheads showing direction of increasing t. A helix (/ ˈhiːlɪks /; pl. helices) is a shape like a cylindrical coil spring or the thread of a machine screw. It is a type of smooth space curve with tangent lines at a constant angle to a fixed axis.
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 the local structure that is most easily predicted from a sequence of amino ...
The digits of pi extend into infinity, and pi is itself an irrational number, meaning it can’t be truly represented by an integer fraction (the one we often learn in school, 22/7, is not very ...
All three angles are at 180° in the conformation shown. In biochemistry, a Ramachandran plot (also known as a Rama plot, a Ramachandran diagram or a [φ,ψ] plot), originally developed in 1963 by G. N. Ramachandran, C. Ramakrishnan, and V. Sasisekharan, [1] is a way to visualize energetically allowed regions for backbone dihedral angles ( also ...
A 310 helix is a type of secondary structure found in proteins and polypeptides. Of the numerous protein secondary structures present, the 3 10 -helix is the fourth most common type observed; following α-helices, β-sheets and reverse turns. 3 10 -helices constitute nearly 10–15% of all helices in protein secondary structures, and are ...
Don't rely on bloviating pundits to tell you who'll prevail on Hollywood's big night. The Huffington Post crunched the stats on every Oscar nominee of the past 30 years to produce a scientific metric for predicting the winners at the 2013 Academy Awards. Follow the Oscars with live updates here. Key Dates.