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IBM System/4 Pi, a family of avionics computers 4Pi microscope , a microscope that uses interference and fluorescence computers 4×π = 12.56637..., the solid angle of a complete sphere measured in steradians
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 hydrolysis starts with the enzyme PI 4-kinase alpha converting PI into PI 4-phosphate , which is then converted into PI (4,5) biphosphate (PI(4,5)P 2) by the enzyme PI 4-phosphate-5-kinase . PI(4,5)P 2 is then hydrolysed by phospholipase C ( PLC ) and forms the second messengers, inositol (1,4,5) triphosphate ( IP 3 ) and diacylglycerol ( DG ).
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 ]
Helices are important in biology, as the DNA molecule is formed as two intertwined helices, and many proteins have helical substructures, known as alpha helices. The word helix comes from the Greek word ἕλιξ, "twisted, curved". [1] A "filled-in" helix – for example, a "spiral" (helical) ramp – is a surface called a helicoid. [2]
(In geometry, the term sphere properly refers only to the surface, so a sphere thus lacks volume in this context.) For an ordinary three-dimensional ball, the SA:V can be calculated using the standard equations for the surface and volume, which are, respectively, S A = 4 π r 2 {\displaystyle SA=4\pi {r^{2}}} and V = ( 4 / 3 ) π r 3 ...
Molecular geometry is the three-dimensional arrangement of the atoms that constitute a molecule. It includes the general shape of the molecule as well as bond lengths , bond angles , torsional angles and any other geometrical parameters that determine the position of each atom.
Phosphatidylinositol 4,5-bisphosphate or PtdIns(4,5)P 2, also known simply as PIP 2 or PI(4,5)P 2, is a minor phospholipid component of cell membranes. PtdIns(4,5)P 2 is enriched at the plasma membrane where it is a substrate for a number of important signaling proteins. [1] PIP2 also forms lipid clusters [2] that sort proteins. [3] [4] [5]