Search results
Results from the WOW.Com Content Network
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 ]
The Dictionary of Protein Secondary Structure, in short DSSP, is commonly used to describe the protein secondary structure with single letter codes. The secondary structure is assigned based on hydrogen bonding patterns as those initially proposed by Pauling et al. in 1951 (before any protein structure had ever been experimentally determined).
The conventional definition in pre-calculus geometry is the ratio of the circumference of a circle to its diameter: π = C D . {\displaystyle \pi ={\frac {C}{D}}.} However, because the circumference of a circle is not a primitive analytical concept, this definition is not suitable in modern rigorous treatments.
where C is the circumference of a circle, d is the diameter, and r is the radius.More generally, = where L and w are, respectively, the perimeter and the width of any curve of constant width.
Fractal geometry lies within the mathematical branch of measure theory. One way that fractals are different from finite geometric figures is how they scale . Doubling the edge lengths of a filled polygon multiplies its area by four, which is two (the ratio of the new to the old side length) raised to the power of two (the conventional dimension ...
The number π (/ p aɪ /; spelled out as "pi") is a mathematical constant that is the ratio of a circle's circumference to its diameter, approximately equal to 3.14159.The number π appears in many formulae across mathematics and physics.
In practice, the major effect seen is that of the presence or absence of the methylene group at Cβ. [5] Glycine has only a hydrogen atom for its side chain, with a much smaller van der Waals radius than the CH 3 , CH 2 , or CH group that starts the side chain of all other amino acids.
Biology is the scientific study of life. [ 1 ] [ 2 ] [ 3 ] It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. [ 1 ] [ 2 ] [ 3 ] For instance, all organisms are made up of at least one cell that processes hereditary information encoded in genes , which can be transmitted ...